III-N Technology€¦ · business development by helping them to understand their IP environment...

Coordinated by CRHEA-CNRS research laboratory, this monthly newsletter is produced by Knowmade with collaboration from the managers of GANEX groups. The newsletter presents a selection of newest scientific publications, patent applications and press releases related to III-Nitride semiconductor materials (GaN, AlN, InN and alloys)

All issues on www.ganex.fr in Veille section. Free subscription http://www.knowmade.com/ganex

GANEX Cluster of Excellence (Labex, 2012-2019) GANEX is a cluster gathering French research teams involved in GaN technology. The objective of GANEX is to strengthen the position of French academic players in terms of knowledge and visibility, and reinforce the French industrials in terms of know-how and market share. www.ganex.fr

KnowMade We Know Technology, We Know Patents Knowmade is a Technology Intelligence and IP Strategy consulting company specialized in analysis of patents and scientific information. The company supports R&D organizations, industrial companies and investors in their business development by helping them to understand their IP environment and follow technology trends. Knowmade is involved in Microelectronics & Optoelectronics, Compound Semiconductors, IC Manufacturing & Advanced Packaging, Power & RF Devices, MEMS & Sensors, Photonics, Micro & Nanotechnology, Biotech/Pharma, MedTech & Medical Devices, and Agri-Food. Knowmade provides prior art search, patent landscape analysis, patent valuation, freedom-to-operate analysis, litigation and licensing support, scientific literature landscape, technology scouting and tracking. Knowmade’s analysts combine their technical and patent expertise by using powerful analytics tools and proprietary methodologies to deliver relevant patent analyses and scientific reviews. www.knowmade.com

GANEX Newsletter No. 48 January 2017

III-N Technology

Click here

../2013/Newsletter%202013/Newsletter%2002%20-%20Feb%202013%20(4-5-6-7)/www.ganex.frhttp://www.knowmade.com/ganexhttp://www.ganex.fr/http://www.knowmade.com/http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade

GANEX | Newsletter No. 48 - III-N Technology 2

METHODOLOGY

Each month 250+ new scientific publications

120+ new patent applications 20+ new press releases

Sources 10+ scientific journal editors

Elsevier, IOP, IEEE, Wiley, Springer, APS, AIP, AVS, ECS, Nature, Science …

10+ specialist magazines Semiconductor Today, ElectoIQ, i-micronews,

Compound Semiconductor, Solid State Technology … 5+ open access database: FreeFulPDF, DOAJ …

Patent database: Questel-Orbit

Selection by III-N French

experts

GANEX monthly newsletter

Click here

http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


TABLE OF CONTENTS (clickable links to chapters)

SCIENTIFIC PUBLICATION ................................................................................................................... 4

GROUP 1 - LEDs and Lighting ................................................................................................................... 4

GROUP 2 - Laser and Coherent Light ....................................................................................................... 8

GROUP 3 - Power Electronics ................................................................................................................. 11

GROUP 4 - Advanced Electronics and RF ............................................................................................... 13

GROUP 5 – MEMS and Sensors .............................................................................................................. 16

GROUP 6 - Photovoltaics and Energy harvesting ................................................................................... 19

GROUP 7 - Materials, Technology and Fundamental............................................................................. 22

PRESS RELEASE ................................................................................................................................ 34

PATENT APPLICATION ...................................................................................................................... 42

Click here

http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


SCIENTIFIC PUBLICATION Selection of new scientific articles

GROUP 1 - LEDs and Lighting Group leader: Benjamin Damilano (CRHEA-CNRS)

Information selected by Benjamin Damilano (CRHEA-CNRS)

Reduction of contact resistance in V-based electrode for high AlN molar fraction n-type AlGaN by using thin SiNx intermediate layer Faculty of Science and Technology, Meijo University, Nagoya 468-0073, Japan Physica status solidi (c) http://dx.doi.org/10.1002/pssc.201600243

We found out the reduction of contact resistance in V-based electrode for high AlN molar fraction n-type AlGaN by using thin SiNx intermediate layer. The contact resistivity for n -type Al0.70Ga0.30N with the V/Al/Ni/Au electrode using SiNx intermediated layer reached 1.13 × 10-6 Ω cm2. Moreover, contact resistivity using SiNx intermediated layer had been reduced more than one order of magnitude in all AlN molar fractions from 0.62 to 0.87. Using this electrode, we also demonstrated UV light-emitting diodes (LEDs) on n -type Al0.70Ga0.30N underlying layer with an emission wavelength of approximately 283 nm. An operating LED voltage using a V/Al/Ni/Au electrode with SiNx intermediated layer was 3.3 V lower at 100 mA current injection than that without SiNx intermediated layer. Simultaneous light emission and detection of InGaN/GaN multiple quantum well diodes for in-plane visible light communication Grünberg Research Centre, Nanjing University of Posts and Telecommunications, China Optics Communications http://dx.doi.org/10.1016/j.optcom.2016.10.070

This paper presents the design, fabrication, and experimental characterization of monolithically integrated p-n junction InGaN/GaN multiple quantum well diodes (MQWDs) and suspended waveguides. Suspended MQWDs can be used as transmitters and receivers simultaneously, and suspended waveguides are used for light coupling to create an in-plane visible light communication system. Compared to the waveguide with separation trench, the calculated total light efficiency is increased from 18% to 22% for the continuous waveguide. The MQWDs are characterized by their typical current-voltage performance, and the pulse excitation measurements confirm that the InGaN/GaN MQWDs can achieve the light emission and photodetection at the same time. The photocurrent measurements indicate that the photocurrent is modulated by a bias voltage and that the photons are being supplied from another transmitter. An experimental demonstration is presented showing that the proposed device works well for in-plane full-duplex communication using visible light. Defect-Related Degradation of AlGaN-Based UV-B LEDs Department of Information Engineering, University of Padua, Padua, Italy IEEE Transactions on Electron Devices https://doi.org/10.1109/TED.2016.2631720

This paper describes an extensive analysis of the degradation of (InAlGa)N-based UV-B light-emitting diodes (LEDs) submitted to constant current stress. This paper is based on combined

Click here

http://dx.doi.org/10.1002/pssc.201600243http://dx.doi.org/10.1016/j.optcom.2016.10.070https://doi.org/10.1109/TED.2016.2631720http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


electrical characterization, spectral analysis of the emission, deep-level transient spectroscopy (DLTS) and photocurrent (PC) spectroscopy. The results of this analysis demonstrate that: 1) UV-B LEDs show a gradual degradation when submitted to constant current stress; the decrease in optical power is stronger for low measuring current levels, indicating that degradation is related to the increase in Shockley–Read–Hall (SRH) recombination; 2) the current–voltage characteristics measured before/during stress show an increase in the current below the turn-on voltage, that is ascribed to the increase in trap-assisted tunneling (TAT) components; and 3) DLTS analysis and PC spectroscopy measurements were carried out to identify the properties of the defects responsible for the degradation of the optical and electrical characteristics. The results indicate that stress induces or activates defects centered around 2.5 eV below the conduction band edge. These defects, close to midgap, can explain both the increased SRH recombination and the increase in TAT components detected after stress. Moreover, the DLTS measurements allowed to identify the signature of Mg-related acceptor traps. Combining High Hole Concentration in p-GaN and High Mobility in u-GaN for High p-Type Conductivity in a p-GaN/u-GaN Alternating-Layer Nanostructure Department of Electrical Engineering, Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan IEEE Transactions on Electron Devices https://doi.org/10.1109/TED.2016.2631148

p-GaN/u-GaN alternating-layer nanostructures are grown with molecular beam epitaxy to show a low p-type resistivity level of 0.038 Ω -cm. The obtained low resistivity is due to the high hole mobility in the u-GaN layers, which serve as effective transport channels of holes diffused from the neighboring p-GaN layers. The Mg doping in a thin p-GaN layer can lead to a high Mg-doping concentration for supplying holes to the neighboring u-GaN layers. Simulations based on a 1-D drift diffusion charge control model and the Brooks–Herring theory of ionized impurity

scattering are undertaken to first obtain the depth-dependent distributions of hole concentration, mobility, and, hence, resistivity. Then, weighted averaging processes are used for evaluating the effective hole concentration, mobility, and resistivity of a p-GaN/u-GaN alternating-layer nanostructure to give consistent results with the measured data. Efficiency enhancement of InGaN/GaN light-emitting diodes with pin-doped GaN quantum barrier Institut für Mikrowellentechnik und Photonik, Technische Universität Darmstadt, Merckstraße 25, 64283 Darmstadt, Germany Department of Information Technologies, Mathematics and Physics, Comrat State University, Galatsan Street 17, MD-3800 Comrat, Moldova Department of High Frequency Electronics, Technische Universität Darmstadt, Merckstraße 25, 64283 Darmstadt, Germany Journal of Physics D: Applied Physics http://dx.doi.org/10.1088/1361-6463/50/3/035108

Blue InGaN/GaN light-emitting diodes with undoped, heavily Si-doped, Si delta-doped, heavily Mg-doped, Mg delta-doped, and Mg–Si pin-doped GaN barrier are investigated numerically. The simulation results demonstrate that the Mg–Si pin-doping in the GaN barrier effectively reduces the polarization-induced electric field between the InGaN well and the GaN barrier in the multiple quantum well, suppresses the quantum-confined Stark effect, and enhances the hole injection and electron confinement in the active region. For this light-emitting diode (LED) device structure, we found that the turn-on voltage is 2.8 V, peak light emission is at 415.3 nm, and internal quantum efficiency is 85.9% at 100 A cm−2. It is established that the LED device with Mg–Si pin-doping in the GaN barrier has significantly improved efficiency and optical output power performance, and lower efficiency droop up to 400 A cm−2 compared with LED device structures with undoped or Si(Mg)-doped GaN barrier.

https://doi.org/10.1109/TED.2016.2631148http://dx.doi.org/10.1088/1361-6463/50/3/035108

KnowMade


Significant performance enhancement of InGaN/GaN nanorod LEDs with multi-layer graphene transparent electrodes by alumina surface passivation Max Planck Institute for the Science of Light, Staudtstr. 2, D-91058 Erlangen, Germany Institute of Optics, Information and Photonics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7/B2, 91058 Erlangen, Germany Institut für Nanoarchitekturen für die Energieumwandlung, Helmholtz-Zentrum Berlin für Matierialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany Nanotechnology http://dx.doi.org/10.1088/1361-6528/28/5/055201

Nanotextured surfaces provide an ideal platform for efficiently capturing and emitting light. However, the increased surface area in combination with surface defects induced by nanostructuring e.g. using reactive ion etching (RIE) negatively affects the device's active region and, thus, drastically decreases device performance. In this work, the influence of structural defects and surface states on the optical and electrical performance of InGaN/GaN nanorod (NR) light emitting diodes (LEDs) fabricated by top-down RIE of c-plane GaN with InGaN quantum wells was investigated. After proper surface treatment a significantly improved device performance could be shown. Therefore, wet chemical removal of damaged material in KOH solution followed by atomic layer deposition of only 10 $\mathrm{nm}$ alumina as wide bandgap oxide for passivation were successfully applied. Raman spectroscopy revealed that the initially compressively strained InGaN/GaN LED layer stack turned into a virtually completely relaxed GaN and partially relaxed InGaN combination after RIE etching of NRs. Time-correlated single photon counting provides evidence that both treatments—chemical etching and alumina deposition—reduce the number of pathways for non-radiative recombination. Steady-state photoluminescence revealed that the luminescent performance of the NR LEDs is increased by about 50% after KOH and 80% after additional alumina passivation. Finally, complete NR LED devices with a suspended graphene contact were fabricated, for which the

effectiveness of the alumina passivation was successfully demonstrated by electroluminescence measurements. Highly linearly polarized white light emission from InGaN light-emitting diode with nanograting-integrated fluorescent ceramics College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125, China Applied Physics Express http://dx.doi.org/10.7567/APEX.10.012101

We proposed and demonstrated a linearly polarized white light emission from an InGaN light-emitting diode with nanograting-integrated fluorescent ceramics. By incorporating a dielectric layer with low refractive index between multilayer nanogratings and a fluorescent ceramic, both high TM transmission (TMT) and high extinction ratio (ER) were effectively achieved across the entire range of white light. An ER higher than 20 dB and a TMT of 60% were obtained experimentally for a GaN/fluorescent-ceramic-integrated white LED with a multilayer grating of 150 nm period. The fluorescent-ceramic-integrated structure showed possibilities of implementing a polarized white LED with high performance. Transferring the bendable substrateless GaN LED grown on a thin C-rich SiC buffer layer to flexible dielectric and metallic plates Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road Sec. 4, Taipei 10617, Republic of China Department of Photonics and Department of Physics, National Sun Yat-sen University, No. 70, Lien-Hai Rd., Kaohsiung 804, Taiwan Department of Physics, National Taiwan University, 1, Roosevelt Road Sec. 4, Taipei 106, Republic of China Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan

http://dx.doi.org/10.1088/1361-6528/28/5/055201http://dx.doi.org/10.7567/APEX.10.012101

KnowMade


Journal of Materials Chemistry C http://dx.doi.org/10.1039/C6TC04318F

By growing an epitaxial GaN LED on C-rich a-SiC buffer deposited SiO2/Si substrate, the simplified transfer to versatile flexible metallic/dielectric membranes is demonstrated. Both the high growth temperature at 1000 °C and the slow deposition rate played important roles in the meticulous MOCVD growth of n-GaN along the surface normal of the a-SiC at the very beginning. High substrate temperature facilitated the refinement of C-rich SiC buffer from amorphous to partially crystalline with (0004)-orientation, which effectively reduces the lattice mismatch between n-GaN and SiC at the interface so as to gradually improve the crystalline n-GaN regrowth. The substrateless GaN LED transferred to flexible copper plates showed reduced turn-on voltage of 2.6 V, enhanced output power of 370 mW, enlarged power-to-current slope of 1.24 W A−1, increased external quantum efficiency of 45%, and reduced efficiency droop of 15% under a bias of 300 mA. The thermal conductivity of the transferred substrate affected the EL peak wavelength shift of the substrateless GaN LED on SiC buffer. Heating the GaN LED on flexible copper plate to 65 °C only reduced its power by 10% and red-shifted its wavelength by 1 nm under a bias at 100 mA; the Auger effect resulted in a degraded EQE of 39.1% and an enlarged EQE droop of 8.5%. Bending the surface diameter of the curvature of the copper plate to 1.2 cm decayed the output power by 12% and red-shifted the EL peak by 5 nm because of the lattice strain induced quantum confined Stark effect (QCSE). Such a bendable substrateless GaN LED transferred to flexible membrane with superior heat dissipation and bending tolerance is a desired lighting element for green photonics in this era.

http://dx.doi.org/10.1039/C6TC04318F

KnowMade


GROUP 2 - Laser and Coherent Light Group leader: Bruno Gayral (CEA)

Information selected by Knowmade

All-optical guided resonance tuning in hybrid GaN/Si microring induced by non-radiatively trapped injected hot electrons Department of Nanomechanics, Graduate School of Engineering, Tohoku University, 6-6-1 Aoba, Aramaki, Aoba, Sendai, Miyagi 980-8579 Japan Optics Express https://doi.org/10.1364/OE.24.029643

Advanced Si/III–V nanophotonics that emerged in the last decade has already founded the on-chip optical interconnect technology for future integrated systems on chip. New possibilities of light-on-chip applications beside signal transmissions, such as, all-optical sensing, have been given but small attention. Here, all-optical ultraviolet (UV)-sensitive guided resonance tuning in a hybrid GaN/Si microring resonator (HMR) was studied. Resonance redshifting by free-space UV pumping resulted in a 12 dB guided-mode modulation at the 1560 nm telecommunication wavelength. Investigations by experiments, theory, and simulations indicated the origin of the tuning mechanism from hot-electron heat extraction via defects-assisted non-radiative recombinations and electron-phonon interactions. A photothermal tuning efficiency of 73 pm/mW was attained at a pump power of 850 μW, thank to photothermal energy directly generated in the HMR. The UV-sensitive visible-blind all-optical tuning in the HMR may benefit all-optical UV sensing for the optical data era to come.

III-Nitride-on-silicon microdisk lasers from the blue to the deep ultra-violet Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de, Montpellier, F-34095 Montpellier, France Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bâtiment 220, F-91045 Orsay, France Centre de Recherche pour l'Hetero-Epitaxie et ses Applications (CRHEA)-CNRS, Rue Bernard Gregory, F-06560 Valbonne, France Université Grenoble Alpes, F-38000 Grenoble, France CEA, INAC-PHELIQS, Nanophysique et Semiconducteurs Group, F-38000 Grenoble, France Applied Physics Letters http://dx.doi.org/10.1063/1.4971357

We present a series of microdisk lasers realized within the same GaN-on-Si photonic platform scheme, and operating at room temperature under pulsed optical pumping over a broad spectral range extending over λ = 275 nm–470 nm. The III-nitride microdisks embed either binary GaN/AlN multiple quantum wells (MQWs) for UV operation, or ternary InGaN/GaN MQWs for violet and blue operation. This demonstrates the versatility of this nitride-on-silicon platform, and the realization on this platform of efficient active layers for lasing action over a 200 nm broad UV to visible spectral range. We probe the lasing threshold carrier density over the whole spectral range and found that it is similar whatever the emission wavelength for these Q > 1000 microdisk resonators with a constant material quality until quantum confined Stark effect takes over. The threshold is also found independent of microdisk diameters from 3 to 12 μm, with a β factor intermediate between the one of vertical cavity lasers and the one of small modal volume “thresholdless” lasers.

Click here

https://doi.org/10.1364/OE.24.029643http://dx.doi.org/10.1063/1.4971357http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


A lithographic approach for quantum dot-photonic crystal nanocavity coupling in dilute nitrides National Research Council, Institute for Photonics and Nanotechnologies (IFN-CNR), Via Cineto Romano 42, 00156 Rome, Italy Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro 5, 00185 Roma, Italy Department of Electronic and Electrical Engineering, University of Sheffield, 3 Solly Street, Sheffield S1 4DE, United Kingdom IOM-CNR Laboratorio TASC, S. S. 14, Km 163.5, 34149 Trieste, Italy LENS and Dipartimento di Fisica,Università di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, FI, Italy Microelectronic Engineering http://dx.doi.org/10.1016/j.mee.2016.12.003

We report on a novel lithographic approach for the fabrication of integrated quantum dot (QD)-photonic crystal (PhC) nanocavity systems. We exploit unique hydrogen's ability to tailor the band gap energy of dilute nitride semiconductors to fabricate isolated site-controlled QDs via a spatially selective hydrogenation at the nanometer-scale. A deterministic integration of the realized site-controlled QDs with PhC nanocavities is provided by the inherent realignment precision (~ 20 nm) of the electron beam lithography system used for the fabrication of both QDs and PhC cavities. A detailed description of the fabrication steps leading to the realization of integrated QD-PhC cavity systems is provided, together with the experimental evidence of a weak coupling effect between the single-photon emitter and the PhC cavity. Optically Pumped DFB Lasers Based on GaN Using 10th-Order Laterally Coupled Surface Gratings Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany Institut für Festkörperphysik, Technische Universität Berlin, Berlin, Germany IEEE Photonics Technology Letters https://doi.org/10.1109/LPT.2016.2630078

An optically pumped GaN-based laser structure with 10th-order laterally coupled surface grating is demonstrated. The fabrication involved i-line

photolithography and dry etching, avoiding more complex technologies such as multiple epitaxy steps. The lasing threshold of the laterally coupled distributed-feedback (LC-DFB) laser was similar to that of a ridge waveguide Fabry–Perot (RW-FP) laser. Single-peak emission with a full width at half maximum of 0.06 nm at 404.2 nm was achieved for LC-DFB lasers. In contrast to the RW-FP lasers, the LC-DFB laser is shown to exhibit a smaller shift of the emission wavelength with temperature. Optical polarization control of photo-pumped stimulated emissions at 238 nm from AlGaN multiple-quantum-well laser structures on AlN substrates Sensor Electronic Technology, Inc., Columbia, SC 29209, U.S.A. Rensselaer Polytechnic Institute, Troy, NY 12180, U.S.A. Applied Physics Express http://dx.doi.org/10.7567/APEX.10.012702

We demonstrate the capability to control the optical polarization of room-temperature stimulated emissions (SEs) at 238–239 nm from optically pumped AlGaN multiple-quantum-well (MQW) heterostructures on bulk AlN. The results of structural and optical characterizations provided evidence that altering the strain state in the pseudomorphically grown MQW laser structures enabled the switching of the polarization direction of the SE from predominantly transverse electric (TE) at 238 nm to predominantly transverse magnetic (TM) at 239 nm. The SE observed at 238 nm represents the shortest peak wavelength with TE polarization yet reported for AlGaN materials grown on any type of substrate. Optical characterization of InGaN/GaN quantum well active region of green laser diodes Suzhou Institute of Nano-tech and Nano-bionics, University of Chinese Academy of Science, Suzhou 215123, People's Republic of China Key Laboratory of Nanodevices and Applications, Chinese Academy of Science, Suzhou 215123, People's Republic of China Applied Physics Express http://dx.doi.org/10.7567/APEX.10.012701

http://dx.doi.org/10.1016/j.mee.2016.12.003https://doi.org/10.1109/LPT.2016.2630078http://dx.doi.org/10.7567/APEX.10.012702http://dx.doi.org/10.7567/APEX.10.012701

KnowMade


We performed the optical characterization of InGaN/GaN quantum well (QW) active regions of green laser diodes (LDs) with different threshold current densities by temperature-dependent photoluminescence (PL) analysis. The internal quantum efficiency (IQE) was evaluated to be 39 and 59% for green LDs with threshold current densities of 8.50 and 1.85 kA cm−2, respectively. Additional nonradiative recombination centers with an activation energy of 10 meV were found in the sample with the lower IQE, which is attributed to defects located at the interface of InGaN/GaN QWs. Optically-free-standing InGaN microdisks with metallic reflectors Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Japanese Journal of Applied Physics http://dx.doi.org/10.7567/JJAP.56.01AD04

The optical properties of free-standing thin-film microdisks with NiAg metallic reflectors are compared with those with an indium tin oxide (ITO) interfacial layer. The microdisks have been fabricated by a combination of microsphere lithography and laser lift-off processes. Optical-pumped lasing from the microdisk with NiAg reflector has been observed, with reduced threshold and higher quality factor compared those with ITO layers, attributed to improved optical confinement due to the reflectivity of the Ag coating. The results are supported by three-dimensional (3D) finite-difference-time-domain (FDTD) simulations.

http://dx.doi.org/10.7567/JJAP.56.01AD04

KnowMade


GROUP 3 - Power Electronics Group leader: Frédéric Morancho (LAAS-CNRS)

Information selected by Frédéric Morancho (LAAS-CNRS) and Yvon Cordier (CRHEA-CNRS)

High-Voltage and Low-Leakage AlGaN/GaN Tri-Anode Schottky Diodes With Integrated Tri-Gate Transistors Power and Wide-band-gap Electronics Research Laboratory (POWERlab), École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland IEEE Electron Device Letters https://doi.org/10.1109/LED.2016.2632044

We present AlGaN/GaN nanostructured Schottky barrier diodes (SBDs) on silicon substrate with high breakdown voltage ( VBR ) and low reverse leakage current ( IR ), based on a hybrid of tri-anode and tri-gate architectures. The fabricated SBDs presented a small turn-on voltage ( Von ) of 0.76 ± 0.05 V, since the tri-anode architecture formed direct Schottky contact to the 2-D electron gas (2DEG). The reverse characteristic was controlled electrostatically by an embedded tri-gate transistor, instead of relying only on the Schottky barrier. This resulted in low IR below 10 and 100 nA/mm at large reverse biases up to 500 and 700 V, respectively. In addition, these devices exhibited record VBR up to 1325 V at IR of 1 μA /mm, rendering an excellent high-power figure-of-merit (FOM) of 939 MW/cm2 and demonstrating the significant potential of nanostructured GaN SBDs for future efficient power conversion. High-Performance 500 V Quasi- and Fully-Vertical GaN-on-Si pn Diodes Microsystems Technology Laboratories, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 USA IEEE Electron Device Letters https://doi.org/10.1109/LED.2016.2646669

This letter demonstrates quasi- and fully-vertical GaN-on-Si pn diodes with record performance. The optimized device structure employs a highly conductive (ND>1020 cm-3) current collecting layer and a lightly carbon-doped drift layer. With this optimization, a differential specific on-resistance (Ron) of 0.8-1 mΩ·cm2, a breakdown voltage (BV) over 500 V and a high forward current (~kA/cm2) were demonstrated. Excellent Ron and BV performance up to 300 oC was also obtained. A small reverse recovery time of 50 ns was demonstrated under switching conditions. With a Baliga’s figure of merit over 0.32 GW/cm2, these devices shows the great potential of low-cost GaN-on-Si vertical devices for future power applications. Mg-compensation effect in GaN buffer layer for AlGaN/GaN high-electron-mobility transistors grown on 4H-SiC substrate Convergence Center for Advanced Nano Semiconductor (CANS), Department of Nano-Optical Engineering, Korea Polytechnic University (KPU), Siheung, Gyeonggi 427-793, Republic of Korea Japanese Journal of Applied Physics http://dx.doi.org/10.7567/JJAP.56.015502

The present study investigated the Mg doping effect in the gallium nitride (GaN) buffer layers (BLs) of AlGaN/GaN high-electron-mobility transistor (HEMT) structures grown on semi-insulating 4H-SiC substrates by metal organic chemical vapor deposition. When the Mg concentration was increased from 3 × 1017 to 8 × 1018 cm−3, the crystal quality slightly deteriorated, whereas electrical properties were significantly changed. The buffer leakage increased approximately 50 times from 0.77 to 39.2 nA at −50 V with the Mg doping concentration. The Mg-compensation effect and

Click here

https://doi.org/10.1109/LED.2016.2632044https://doi.org/10.1109/LED.2016.2646669http://dx.doi.org/10.7567/JJAP.56.015502http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


electron trapping effect were observed at Mg concentration of 3 × 1017 and 8 × 1018 cm−3, respectively, which were confirmed by an isolation leakage current test and low-temperature photoluminescence. When the BL was compensated, the two-dimensional electron gas (2DEG) mobility and sheet carrier concentration of the HEMTs were 1560 cm2 V−1 s−1 and 5.06 × 1012 cm−2, respectively. As a result, Mg-doped GaN BLs were demonstrated as a candidates of semi-insulating BLs for AlGaN/GaN HEMT. Review—Ultra-Wide-Bandgap AlGaN Power Electronic Devices Sandia National Laboratories, Albuquerque, New Mexico 87185, USA ECS Journal of Solid State Science and Technology http://dx.doi.org/10.1149/2.0111702jss

“Ultra” wide-bandgap semiconductors are an emerging class of materials with bandgaps greater than that of gallium nitride (EG > 3.4 eV) that may ultimately benefit a wide range of applications, including switching power conversion, pulsed power, RF electronics, UV optoelectronics, and quantum information. This paper describes the progress made to date at Sandia National Laboratories to develop one of these materials, aluminum gallium nitride, targeted toward high-power devices. The advantageous material properties of AlGaN are reviewed, questions concerning epitaxial growth and defect physics are covered, and the processing and performance of vertical- and lateral-geometry devices are described. The paper concludes with an assessment of the outlook for AlGaN, including outstanding research opportunities and a brief discussion of other potential applications.

Vertical GaN Junction Barrier Schottky Diodes U.S. Naval Research Laboratory, Washington, DC 20375, USA ECS Journal of Solid State Science and Technology http://dx.doi.org/10.1149/2.0041701jss

Vertical GaN junction barrier Schottky (JBS) diodes are demonstrated. The JBS p-type grid was formed by Mg-implantation into a 10 μm thick unintentionally doped GaN homoepitaxial drift layer, grown by metal organic chemical vapor deposition (MOCVD). Then, symmetrical multi-cycle rapid thermal annealing (SMRTA) repaired implantation damage and activated the Mg ions. This process includes deposition of an AlN capping layer, annealing in a nitrogen overpressure, and rapid heating and cooling pulsed annealing. In addition, PiN diodes and Schottky barrier diodes (SBDs) were fabricated on the same substrate for comparison. The JBS diode demonstrates forward conduction characteristics dominated by the Schottky barrier (turn-on voltage ∼0.5 V), and reverse breakdown voltage comparable to the PiN diode (−610 V).

http://dx.doi.org/10.1149/2.0111702jsshttp://dx.doi.org/10.1149/2.0041701jss

KnowMade


GROUP 4 - Advanced Electronics and RF Group leader: Jean-Claude Dejaeger (IEMN)

Information selected by Jean-Claude Dejaeger (IEMN) and Yvon Cordier (CRHEA-CNRS)

Demonstration of flexible thin film transistors with GaN channels Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey Applied Physics Letters http://dx.doi.org/10.1063/1.4971837

We report on the thin film transistors (TFTs) with Gallium Nitride (GaN) channels directly fabricated on flexible substrates. GaN thin films are grown by hollow cathode plasma assisted atomic layer deposition (HCPA-ALD) at 200 °C. TFTs exhibit 103 on-to-off current ratios and are shown to exhibit proper transistor saturation behavior in their output characteristics. Gate bias stress tests reveal that flexible GaN TFTs have extremely stable electrical characteristics. Overall fabrication thermal budget is below 200 °C, the lowest reported for the GaN based transistors so far. Influence of mesa edge capacitance on frequency behavior of millimeter-wave AlGaN/GaN HEMTs State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China Science and Technology of ASIC Lab, Hebei Semiconductor Research Institute, Shijiazhuang 050051, People's Republic of China Solid-State Electronics http://dx.doi.org/10.1016/j.sse.2016.11.016

The influence of mesa edge capacitance on the frequency characteristics of AlGaN/GaN HEMTs with 90 nm gate length was studied in this paper. To extract mesa edge capacitances, a small-signal equivalent circuit model considering mesa edge capacitances was provided. Based on the model,

the intrinsic gate capacitances of AlGaN/GaN HEMTs with 2 × 20 μm, 2 × 30 μm, 2 × 40 μm, and 2 × 50 μm gate widths were extracted, respectively. Through linear fitting along gate width for the extracted results and simulations, 8.06 fF/μm2 of mesa edge capacitances at Vgs = −4.5 V and Vds = 8 V in the devices with 2 × 20 μm gate width was obtained, which can be about 33.2% of the total gate capacitance. Mesa edge capacitances results in a significant drop of current-gain cut-off frequency (fT), and the effect is more serious in the shorter gate length devices. A Highly Efficient Power Amplifier at 5.8 GHz Using Independent Harmonic Control Division of IT Convergence Engineering, Pohang University of Science and Technology (POSTECH), Gyeongbuk, Republic of Korea IEEE Microwave and Wireless Components Letters https://doi.org/10.1109/LMWC.2016.2630853

An optimal design of a highly efficient power amplifier (PA) is described using independent fundamental and second harmonic impedance control technique. In fabrication of a power amplifier, a tuning method is indispensable because the simulation models of the device and capacitor have some difference with the actual value. To achieve a high drain efficiency, the fundamental and harmonic impedances need to be accurately optimized. However, as the operating frequency is increased, the matching circuit becomes sensitive and it is difficult to realize the accurate optimum matching. To solve the problem, the matching circuit of the PA adopts the independent harmonic control circuit using the characteristic of a quarter-wavelength microstrip line. A power amplifier with the concept is designed and implemented using a Cree GaN HEMT CGH40035 at 5.8 GHz. The peak

Click here

http://dx.doi.org/10.1063/1.4971837http://dx.doi.org/10.1016/j.sse.2016.11.016https://doi.org/10.1109/LMWC.2016.2630853http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


output power, drain efficiency and gain are 47.2 dBm, 70.2%, and 10.2 dB. Driver Topologies for RF Doherty Power Amplifiers Radio Design Center, Ericsson AB, Gothenburg, Sweden Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden IEEE Microwave and Wireless Components Letters https://doi.org/10.1109/LMWC.2016.2629977

In this letter, class-B, embedded class-B, and Doherty driver topologies are investigated for RF Doherty Power Amplifiers (PAs). The investigation is firstly conducted theoretically and by simulations and then verified by design and implementation of the different topologies at 2.1 GHz using GaN-HEMT transistors. The results show that the highest lineup efficiency can be achieved when using a Doherty driver. Modulated measurements using the same LTE signal and the same digital per-distorter (DPD), show about 2% and 4% higher average lineup efficiency when the Doherty driver is used compared to the class-B and embedded class-B drivers, respectively. Influence of the Heterojunction Spacer on the Performance of AlGaN/GaN/AlGaN Resonant Tunneling Diodes Key Laboratory for Microelectronics, College of Physical Science and Technology, Sichuan University, Chengdu, China IEEE Transactions on Electron Devices https://doi.org/10.1109/TED.2016.2623802

We report on a simulation for an aluminum gallium nitride (AlGaN)/gallium nitride (GaN) resonant tunneling diode (RTD) with a step heterojunction emitter spacer (SHES) at room temperature. An SHES and low Al component barriers were introduced in to AlGaN/GaN RTDs to improve the electronic injection efficiency in to the emitter, reduce the transit time in the collector depletion region, and achieve lattice matching. The substitution of the emitter spacer for the SHES alters the dominant transport mechanism, increases the tunneling current, and restrains the thermionic current. As a result, the

peak current was 1.683 A at 0.39 V and the peak-to-valley current difference was 0.93 A. Output power enhancement in AlGaN/GaN heterostructure field-effect transistors with multilevel metallization Department of Mechanical Engineering, University of Houston, Houston, TX 77204-4006, U.S.A. Department of Printed Electronics Engineering, Sunchon National University, Sunchon, Jeonnam 540-742, Korea Semiconductor Physics Research Center, Department of Semiconductor Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756, Korea Maternals Science and Engineering Program, University of Houston, Houston, TX 77204, U.S.A. IGBT part, System IC R&D, LG Electronics, Seoul 137-724, Korea Texas Center for Superconductivity at UH (TcSUH), University of Houston, Houston, TX 77204, U.S.A. Applied Physics Express http://dx.doi.org/10.7567/APEX.10.016502

To improve wafer utilization efficiency and heat dissipation performance, this paper proposes multilevel metallization-structured, lateral-type AlGaN/GaN heterostructure field-effect transistors (HFETs) on a 150 mm Si substrate using photosensitive polyimide (PSPI) as the intermetal dielectric layer. The maximum drain current of the HFETs is 46.3 A, which is 240% higher than that of conventional AlGaN/GaN HFETs with the same die size. Furthermore, the drain current drop of the HFETs under high-bias operation is reduced from 14.07 to 8.09%, as compared to that of conventional HFETs. A sub-terahertz broadband detector based on a GaN high-electron-mobility transistor with nanoantennas Low-Energy Electronic System IRG, Singapore–MIT Alliance for Research and Technology Center, Singapore 138602 Department of Electrical and Computer Engineering, National University of Singapore, Singapore 11758 Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR), Singapore 138634 Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.

https://doi.org/10.1109/LMWC.2016.2629977https://doi.org/10.1109/TED.2016.2623802http://dx.doi.org/10.7567/APEX.10.016502

KnowMade


Applied Physics Express http://dx.doi.org/10.7567/APEX.10.014101

We report a sub-terahertz (THz) detector based on a 0.25-µm-gate-length AlGaN/GaN high-electron-mobility transistor (HEMT) on a Si substrate with nanoantennas. The fabricated device shows excellent performance with a maximum responsivity (R v) of 15 kV/W and a minimal noise equivalent power (NEP) of 0.58 pW/Hz0.5 for 0.14 THz radiation at room temperature. We consider these excellent results as due to the design of asymmetric nanoantennas. From simulation, we show that indeed such nanoantennas can effectively enhance the local electric field induced by sub-THz radiation and thereby improve the detection response. The excellent results indicate that GaN HEMTs with nanoantennas are future competitive detectors for sub-THz and THz imaging applications.

http://dx.doi.org/10.7567/APEX.10.014101

KnowMade


GROUP 5 – MEMS and Sensors Group leader: Marc Faucher (IEMN) Information selected by Knowmade

Long thickness-extensional waves in thin film bulk acoustic wave filters affected by interdigital electrodes Piezoelectric Device Laboratory, School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo, Zhejiang 315211, China School of Mechanical and Electrical Engineering, Ningbo Dahongying University, Ningbo, Zhejiang 315175, China Department of Mechanical and Materials Engineering, The University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA Ultrasonics http://dx.doi.org/10.1016/j.ultras.2016.12.004

We studied free vibrations of thin-film bulk acoustic wave filters with interdigital electrodes theoretically using the scalar differential equations by Tiersten and Stevens. The filters are made from AlN or ZnO films on Si substrates with ground and driving electrodes. They operate with thickness-extensional modes. The basic vibration characteristics including resonant frequencies and mode shapes were obtained. Their dependence on various geometric parameters was examined. It was found that for properly design filters there exist trapped modes whose vibrations are strong in regions with a driving electrode and decay away from the electrode edges. These trapped modes are essentially long plate thickness-extensional modes modulated by the electrode fingers. The number of trapped modes is sensitive to the geometric parameters. Humidity sensing and resonant tunneling properties of indium nitride p-n device Department of Microelectronics Engineering, National Kaohsiung Marine University, No.142, Haijhuan Rd., Nanzih Dist., Kaohsiung City 81157, Taiwan (R.O.C.)

Microelectronic Engineering http://dx.doi.org/10.1016/j.mee.2016.12.025

Indium nitride (InN) and indium nitride compound doped oxygen element (InN:O) compounds are grown for application in sensing devices along with the function of microwave properties. The peak-to-valley current ratio (PVCR) of InN/InNO/In/SiO2/Si (III-S) p-n sensing device reached 2.6. The peak current density and peak voltage of the III-S device were as high as 3.67 kA/cm2 and 2.2 V, respectively. The sensing periods were 580 s and 600 s for the adsorption and desorption processes, respectively. The sensing sensitivities at a low RH% from 40% to 70% and at a high RH% from 70% to 90% were 8.3 mΩ/RH% and 7.5 mΩ/RH%, respectively. The resistive cutoff frequency of an III-S device reached 28 GHz at an RH of 40%. The sensitivity of frequency measurement for an III-S device for relative humidity was 1.7 kHz/RH%. GaN Schottky Metal–Semiconductor–Metal UV Photodetectors on Si(111) Grown by Ammonia-MBE Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore Temasek Laboratories@NTU, Nanyang Technological University, Singapore IEEE Sensors Journal https://doi.org/10.1109/JSEN.2016.2622279

For the development of GaN-based ultraviolet (UV) photodetectors, a simple epilayer structure consisting of GaN (600 nm)/AlN (200 nm) was grown on 100-mm Si substrate using ammonia-molecular beam epitaxy growth technique. The epilayers were crack-free and showed good surface and optical quality. Metal–

Click here

http://dx.doi.org/10.1016/j.ultras.2016.12.004http://dx.doi.org/10.1016/j.mee.2016.12.025https://doi.org/10.1109/JSEN.2016.2622279http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


semiconductor–metal (MSM) interdigitated Schottky-based contacts, fabricated using Ni/Au metallic layers, showed a low dark current of 0.43 nA at 15 V. The analysis of dark current as a function of applied bias revealed that the major current conduction mechanism was through thermionic emission over a Schottky barrier of 0.902 eV. Moreover, the Schottky barrier was found to reduce with the bias, which has been attributed to the image force reduction in the devices. The MSM devices exhibited a peak responsivity of 0.183 A/W at an incident wavelength of 362 nm with a UV/visible rejection ratio of 170. The peak responsivity corresponds to external quantum efficiency of ~70%. The devices also showed good linearity and almost flat responsivity with input power for the applied bias beyond 7 V. Suppression of Persistent Photoconductivity in AlGaN/GaN Ultraviolet Photodetectors Using In Situ Heating Department of Electrical Engineering, Stanford University, Stanford, CA, USA Department of Aeronautics and Astronautics, Stanford University, Stanford, CA, USA Department of Mechanical Engineering, Stanford University, Stanford, CA, USA IEEE Electron Device Letters https://doi.org/10.1109/LED.2016.2626388

Photodetectors based on the AlGaN/GaN heterostructure suffer from persistent photoconductivity (PPC) in which recovery from the optical stimulus can take days. This behavior is unsuitable for many applications where reliable and consistent optical response is required. This letter presents a method for suppressing PPC in AlGaN/GaN photodetectors by employing device suspension and in situ heating. The highly conductive two-dimensional electron gas (2DEG) at the interface of AlGaN and GaN serves as both a sensor and a heater (via Joule heating). Microfabricated AlGaN/GaN-on-Si ultraviolet (UV) photodetectors (suspended and unsuspended) were exposed to UV (365 nm) for 60 s and the transient responses were measured under various in situ heating conditions. The measured transient response showed a decay time of ~39 h when the photodetector was not heated and 24 s for a

suspended photodetector with in situ 2DEG heating (270°C with a power of 75 mW). This remarkable suppression of the PPC in AlGaN/GaN UV photodetectors can be attributed to the novel device architecture and in situ heating capability, which enables acceleration of the carrier capture rate during operation. High-speed solar-blind UV photodetectors using high-Al content Al0.64Ga0.36N/Al0.34Ga0.66N multiple quantum wells Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208, U.S.A. Applied Physics Express http://dx.doi.org/10.7567/APEX.10.011004

We demonstrate high-external quantum efficiency (~50%) solar-blind AlGaN p–n junction photodetectors with high-Al content multiple quantum wells (MQWs). A peak responsivity of 0.1 A/W at 250 nm, which falls >103 by 280 nm, indicates that the optical absorption is dominated by the MQW structures. At a reverse bias of 0.5 V, the dark current is

KnowMade


time (144 ms), a high wavelength selectivity (UV-A light response only), an ultrahigh photoresponsivity of 1.74 × 107 A/W and EQE of 6.08 × 109%, a sensitivity of 2 × 104%, and a very large on/off ratio of more than two orders, as well as robust photocurrent stability (photocurrent fluctuation of less than 7% among 4000 s), showing predominant advantages in comparison with other peer semiconductor photodetectors. The outstanding optoelectronic performance of the bicrystalline GaN nanowire UV-A photodetector is further analyzed based on a detailed high-resolution transmission electron microscope (HRTEM) study, and the two separated crystal domains within the GaN nanowires are believed to provide separated and rapid carrier transfer channels. This work paves a solid way toward the integration of high-performance optoelectronic nanodevices based on bicrystalline or horizontally aligned one-dimensional semiconductor nanostructures.

KnowMade


GROUP 6 - Photovoltaics and Energy harvesting Group leader: Eva Monroy (INAC-CEA)

Information selected by Knowmade

Numerical study of InGaN tandem solar cells with intermediate bands Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung City 807, Taiwan Physica status solidi (RRL) - Rapid Research Letters http://dx.doi.org/10.1002/pssr.201600429

Theoretical investigations of InGaN tandem solar cells with intermediate bands (IBs) have been conducted through calculating the diode equation taking into account the radiative and nonradiative recombination currents. The calculated maximum efficiencies of the double-junction cell with one IB in each subcell are 57.85% and 68.37% under AM1.5G one-sun and 46000-sun illuminations, respectively. It has also been observed that the combined device with the top-cell bandgaps of 2.9–3.4 eV (2.6–3.4 eV for full concentration) may have an opportunity to realize the application of over 50% efficiency. We suggest that the optimized width of the IB layer be designed in the range of 1–6 μm if its absorption coefficient is 104–105 cm–1 in the IB region. InGaN-based photoanode with ZnO nanowires for water splitting Research and Development Center for Solid State Lighting, Institute of SemiconductorsChinese Academy of SciencesBeijingChina Department of Materials Science and EngineeringKorea UniversitySeoulRepublic of Korea Research and Development Center for Solid State Lighting, Institute of SemiconductorsChinese Academy of SciencesBeijingChina Nano Convergence http://dx.doi.org/10.1186/s40580-016-0092-8

The water splitting properties of InGaN photoanodes equipped with ZnO nanowires were

examined in this study. Over the solar spectrum range, the absorbance exhibited a remarkable increase due to the enhanced light absorption caused by the ZnO nanowires. By varying the ZnO nanowires length, the photo-to-current density of photoanodes was increased from 0.017 to 0.205 mA/cm2 at 1.23 V versus reversible hydrogen electrode. Consequently, the incident-photon-to-current efficiency was increased by a factor of 5.5 as the ZnO nanowires growth time increased from 2 to 4 h. The results of this research demonstrate the importance of light absorbance and the surface reaction sites of photoanodes on energy harvesting. Theoretical Study and Simulations of an InGaN Dual-Junction Solar Cell Laboratoire LIMOSEUniversité M’hamed Bougara de BoumerdèsBoumerdèsAlgeria Unité de Développement des Equipements Solaires(UDES)Centre de Développement des Energies Renouvelables (CDER)TipazaAlgeria Laboratoire d’Electronique Quantique, Faculté de PhysiqueUSTHBAlgerAlgeria Journal of Electronic Materials http://dx.doi.org/10.1007/s11664-016-5176-z

This study aims to determine the optimal configuration of the dual-junction InGaN solar cell. Several parameters of the dual-InGaN-junction solar cell have been investigated as the band gap combination and the thicknesses of the layers. Physical models and the optical properties of the InxGa1−xN according to the indium content have been used. The dual-junction solar cell has been designed and simulated for each chosen band gap combination. The current densities drawn from the sub-cells were matched by adjusting their emitter layers thicknesses. The best conversion efficiency obtained for the optimized dual-

Click here

http://dx.doi.org/10.1002/pssr.201600429http://dx.doi.org/10.1186/s40580-016-0092-8http://dx.doi.org/10.1007/s11664-016-5176-zhttp://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


junction In0.49Ga0.51N/In0.74Ga0.26N solar cell, under standard conditions, was 34.93% which corresponds to the band gap combination of 1.73 eV/1.13 eV. The short-circuit current density and the open circuit voltage obtained from the tandem cell In0.49Ga0.51N/In0.74Ga0.26N are respectively, 21.3941 mA/cm2 and 1.9144 V. The current mismatch was 0.057%. The effects of the front and back layers thicknesses of the top and bottom cells on the efficiency were also studied. Furthermore, the electrical characteristics of the dual-junction solar cell and its sub-cells were also discussed. Effect of well layer thickness on quantum and energy conversion efficiencies for InGaN/GaN multiple quantum well solar cells Research Center for Nano Devices and Advanced Materials, Nagoya Institute of Technology, Nagoya 466-8555, Japan Innovation Center for Multi-Business of Nitride Semiconductors, Nagoya Institute of Technology, Nagoya 466-8555, Japan Solid-State Electronics http://dx.doi.org/10.1016/j.sse.2016.12.009

We investigated the effect of well layer thicknesses on the external quantum efficiency (EQE) and energy conversion efficiency (ECE) for InGaN/GaN multiple quantum well (MQW) solar cells grown on sapphire substrates by metalorganic chemical vapor deposition. The results indicated that EQE and ECE have maximum values at a specific well thickness. When the well thickness is sufficiently thin, EQE and ECE increase with an increase in the well thickness owing to an increase in light absorption. Then, once the well thickness surpasses a critical thickness, EQE and ECE begin to decrease owing to the influence of nonradiative recombination processes, which was indicated by the static and dynamic photoluminescence analyses. The critical well thickness probably depends not only on the MQW design but also on growth conditions. Further, we confirmed that the increased total thickness of the stacked well layers leads to increased light absorption and thereby contributes to the improvement of solar cell performance. A high short circuit current density of 1.34 mA/cm2 and a high ECE of 1.31% were achieved for a InGaN/GaN

MQW solar cell with a 3.2-nm-thick InGaN well with total well thickness of 115 nm. Butterfly micro bilayer thermal energy harvester geometry with improved performances Université Grenoble Alpes, TIMA Laboratory, F-38031 Grenoble, France CNRS, TIMA Laboratory, F-38031 Grenoble, France STMicroelectronics, Crolles, France Journal of Physics: Conference Series http://dx.doi.org/10.1088/1742-6596/773/1/012094

This paper reports the recent progress of a new technology to scavenge thermal energy, implying a double-step transduction through thermal buckling of a bilayer aluminum nitride / aluminum bridge and piezoelectric transduction. A completely new scavenger design is presented, improving greatly its final performance. The butterfly shape reduces the overall device mechanical rigidity, which leads to a decrease of buckling temperatures compared to previously studied rectangular plates. In a first time we compared performances of rectangular and butterfly plates with an equal thickness of Al and AlN. In a second time, with a thicker Al layer than AlN layer, we will study only butterfly structure in terms of output power and buckling temperatures, and compare it to the previous stack. Crystallographic investigation of aluminium nitride thin films on stainless steel foil for highly efficient piezoelectric vibration energy harvesters Department of Robotics, Tohoku University, 6-6-01, Aramaki-Aoba, Aoba-ku Sendai, Miyagi, 980-8579, Japan Dai Nippon Printing Co., Ltd, 250-1 Wakashiba, Kashiwa, Chiba, 277-0871, Japan Journal of Physics: Conference Series http://dx.doi.org/10.1088/1742-6596/773/1/012049

This study reports piezoelectric properties and crystallographic microstructures of aluminium nitride (AlN, wurtzite structure) thin films on 50 μm thick stainless steel foil. The transverse piezoelectric coefficient d31f and e31f of 10 pm thick AlN films were estimated as -1.42 ± 0.08

http://dx.doi.org/10.1016/j.sse.2016.12.009http://dx.doi.org/10.1088/1742-6596/773/1/012094http://dx.doi.org/10.1088/1742-6596/773/1/012049

KnowMade


μm/V and -0.48 ± 0.03 C/m2 from a tip displacement of the piezoelectric cantilevers. Dielectric constant s33 was measured as 10.5 ± 1.0. An electron beam diffraction pattern by a high-resolution transmission electron microscope and x-ray diffraction pattern showed that abundance ratio of the orientation such as , and of AlN crystal on stainless steel foils increased with increasing thickness.

KnowMade


GROUP 7 - Materials, Technology and Fundamental Group leader: Jean-Christophe Harmand (LPN-CNRS)

NANO

Information selected by Jesús Zúñiga Pérez (CRHEA-CNRS)

Self-Supporting GaN Nanowires/Graphite Paper: Novel High-Performance Flexible Supercapacitor Electrodes State Key Lab of Crystal Materials, Shandong University, Jinan, P. R. China Small http://dx.doi.org/10.1002/smll.201603330

Flexible supercapacitors have attracted great interest as energy storage devices because of their promise in applications such as wearable and smart electronic devices. Herein, a novel flexible supercapacitor electrode based on gallium nitride nanowire (GaN NW)/graphite paper (GP) nanocomposites is reported. The outstanding electrical conductivities of the GaN NW (6.36 × 102 S m−1) and GP (7.5 × 104 S m−1) deliver a synergistically enhanced electrochemical performance that cannot be achieved by either of the components alone. The composite electrode exhibits excellent specific capacitance (237 mF cm−2 at 0.1 mA cm−2) and outstanding cycling performance (98% capacitance retention after 10 000 cycles). The flexible symmetric supercapacitor also manifests high energy and power densities (0.30 mW h cm−3 and 1000 mW cm−3). These findings demonstrate that the GaN/GP composite electrode has significant potential as a candidate for the flexible energy storage devices. Significant performance enhancement of InGaN/GaN nanorod LEDs with multi-layer graphene transparent electrodes by alumina surface passivation Max Planck Institute for the Science of Light, Staudtstr. 2, D-91058 Erlangen, Germany

Institute of Optics, Information and Photonics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7/B2, 91058 Erlangen, Germany Institut für Nanoarchitekturen für die Energieumwandlung, Helmholtz-Zentrum Berlin für Matierialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany Nanotechnology http://dx.doi.org/10.1088/1361-6528/28/5/055201

Nanotextured surfaces provide an ideal platform for efficiently capturing and emitting light. However, the increased surface area in combination with surface defects induced by nanostructuring e.g. using reactive ion etching (RIE) negatively affects the device's active region and, thus, drastically decreases device performance. In this work, the influence of structural defects and surface states on the optical and electrical performance of InGaN/GaN nanorod (NR) light emitting diodes (LEDs) fabricated by top-down RIE of c-plane GaN with InGaN quantum wells was investigated. After proper surface treatment a significantly improved device performance could be shown. Therefore, wet chemical removal of damaged material in KOH solution followed by atomic layer deposition of only 10 $\mathrm{nm}$ alumina as wide bandgap oxide for passivation were successfully applied. Raman spectroscopy revealed that the initially compressively strained InGaN/GaN LED layer stack turned into a virtually completely relaxed GaN and partially relaxed InGaN combination after RIE etching of NRs. Time-correlated single photon counting provides evidence that both treatments—chemical etching and alumina deposition—reduce the number of pathways for non-radiative recombination. Steady-state photoluminescence revealed that the luminescent performance of the NR LEDs is increased by about 50% after KOH and 80% after

Click here

http://dx.doi.org/10.1002/smll.201603330http://dx.doi.org/10.1088/1361-6528/28/5/055201http://www.knowmade.com/ganex-newsletter-satisfaction-survey/

KnowMade


additional alumina passivation. Finally, complete NR LED devices with a suspended graphene contact were fabricated, for which the effectiveness of the alumina passivation was successfully demonstrated by electroluminescence measurements. Scalable manufacturing of boron nitride nanotubes and their assemblies: a review Security and Disruptive Technologies Portfolio, Emerging Technologies Division, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada Applied Quantum Composites Research Center, Korea Institute of Science and Technology (KIST), Wanju 55324, Korea Advanced Materials and Processing Branch, NASA Langley Research Center, Hampton, Virginia 23681-2199, USA National Institute of Aerospace, Hampton, Virginia 23666, USA Semiconductor Science and Technology http://dx.doi.org/10.1088/0268-1242/32/1/013003

Boron nitride nanotubes (BNNTs) are wide bandgap semiconducting materials with a quasiparticle energy gap larger than 6.0 eV. Since their first synthesis in 1995, there have been considerable attempts to develop novel BNNT-based applications in semiconductor science and technology. Inspired by carbon nanotube synthesis methods, many BNNT synthesis methods have been developed so far; however, it has been very challenging to produce BNNTs at a large scale with the structural quality high enough for exploring practical applications. Very recently there has been significant progress in the scalable manufacturing of high-quality BNNTs. In this article, we will review those particular breakthroughs and discuss their impact on semiconductor industries. Freestanding BNNT assemblies such as transparent thin films, yarns or buckypapers are highly advantageous in the development of novel BNNT-based semiconductor devices. The latest achievements in their manufacturing processes will be also presented along with their potential applications. Luminous Efficiency of Ordered Arrays of GaN Nanowires with Subwavelength Diameters

Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5−7, 10117 Berlin, Germany ACS Photonics http://dx.doi.org/10.1021/acsphotonics.6b00551

We investigate the spontaneous emission from ordered arrays of GaN nanowires (NWs) with well-defined diameters, representing the building blocks for light-emitting as well as light-detecting devices integrated on Si substrates. The luminous efficiency of these arrays is observed to decrease by more than an order of magnitude when the NW diameter is increased from 120 nm to 240 nm. A detailed analysis of both steady-state and transient photoluminescence data reveals that this quenching is not caused by a corresponding decrease of the internal quantum efficiency. Hence, we examine the coupling of light into and out of the NW arrays by appropriate numerical simulations. While the change in absorbance is minor in the investigated diameter range, the extraction efficiency for thin NWs is enhanced by an order of magnitude as compared to thick NWs. This phenomenon primarily originates in the efficient coupling of the spontaneous emission to free space for subwavelength diameter NWs. Additionally, our results show that light, which after extraction from a NW propagates laterally, may be diffracted at the periodic array and redirected into free space, thus further enhancing the extraction efficiency for certain NW diameters.

NON/SEMI POLAR Information selected by

Philippe De Mierry (CRHEA-CNRS) Effect of Al incorporation in nonpolar m-plane GaN/AlGaN multi-quantum-wells using plasma-assisted molecular-beam epitaxy University Grenoble-Alpes, 38000 Grenoble, France CEA, INAC-PHELIQS, 38000 Grenoble, France CNRS, Institut Néel, 38000 Grenoble, France Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany Physica status solidi (a) http://dx.doi.org/10.1002/pssa.201600849

http://dx.doi.org/10.1088/0268-1242/32/1/013003http://dx.doi.org/10.1021/acsphotonics.6b00551http://dx.doi.org/10.1002/pssa.201600849

KnowMade


This paper assesses the difficulties associated with Al incorporation in nonpolar m-plane GaN/AlGaN multi-quantum-wells grown on free-standing m-plane GaN. Structures with average Al mole fraction below 6% show atomically flat surfaces and no extended structural defects, in spite of alloy fluctuations up to 30% of the average concentration. Increasing the average Al composition of the alloy above 23% induces anisotropic degradation of the surface morphology, with appearance of elongated features which increase the surface roughness, along with formation of stacking faults, dislocations, and nm-sized Al-rich clusters. The effect of all these structural features on the MQWs optical performance is discussed. GHz bandwidth semipolar (11-22) InGaN/GaN light-emitting diodes Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, Cork, Ireland School of Engineering, University College Cork, Cork, Ireland Optics Letters https://doi.org/10.1364/OL.41.005752

We report on the electrical-to-optical modulation bandwidths of non-mesa-etched semipolar (112¯2112¯2) InGaN/GaN light-emitting diodes (LEDs) operating at 430–450 nm grown on high-quality (112¯2112¯2) GaN templates, which were prepared on patterned (101¯2101¯2) 𝑟r-plane sapphire substrates. The measured frequency response at −3 dB−3 dB of the LEDs was up to 1 GHz. A high back-to-back data transmission rate of above 2.4 Gbps is demonstrated using a non-return-to-zero on-off keying modulation scheme. This indicates that (112¯2112¯2) LEDs are suitable gigabit per second data transmission for use in visible-light communication applications. Structural and electrical properties of semipolar (11-22) AlGaN grown on m -plane (1-100) sapphire substrates RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Saitama University, 255 Shimo-Ohkubo, Sakura-ku, Saitama 338-8570, Japan

Physica status solidi (c ) http://dx.doi.org/10.1002/pssc.201600248

Semipolar III-nitrides have attracted increasing attention because of the reduced piezoelectric field in the active layer. In particular, (11-22) plane is promising due to the small polarization field along the growth axis and the epitaxial matching on m -plane sapphire. The aim of this study was to assess the effect of growth conditions on the structural and electrical properties of Si-doped (11-22) AlGaN. Semipolar AlGaN/AlN layers were grown on m -plane sapphire by metal-organic chemical vapor deposition at different temperatures, V/III ratios, and tetraethylesilane flows. Surface morphology, crystalline quality, and electrical properties of the AlGaN layers were investigated with AFM, XRD, and by Hall measurements, respectively. Faceted growth of (-1103)-oriented GaN domains on an SiO2-patterned m-plane sapphire substrate using polarity inversion Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemoon-gu, Seoul 02447, Republic of Korea Journal of Applied Crystallography http://dx.doi.org/10.1107/S1600576716015077

Heteroepitaxial growth of ({\overline 1}103)-oriented GaN domains on m-plane sapphire is energetically unfavourable in comparison with that of (1{\overline 1}0{\overline 3})-oriented GaN domains, but the faceted domains with ({\overline 1}103)-oriented GaN reveal a more m-facet-dominant configuration than (1{\overline 1}0{\overline 3})-oriented GaN in such a way that the quantum-confined Stark effect can be more effectively suppressed. It is reported here, for the first time, that semipolar ({\overline 1}103)-oriented and faceted GaN domains can be grown on an SiO2-patterned m-plane sapphire substrate by employing polarity inversion of initially nucleated (1{\overline 1}0{\overline 3})-oriented GaN domains. This polarity inversion of semipolar GaN was found to occur when the domains were grown with a 20–37.5 times higher V/III ratio and 70 K lower growth temperature than corresponding parameters for polarity-not-inverted domains. This work opens up a new

https://doi.org/10.1364/OL.41.005752http://dx.doi.org/10.1002/pssc.201600248http://dx.doi.org/10.1107/S1600576716015077

KnowMade


possibility of effective suppression of the quantum-confined Stark effect by polarity-controlled semipolar GaN in an inexpensive manner in comparison with homoepitaxial growth of ({\overline 1}103)-oriented GaN on a GaN substrate. Improved interface properties of GaN metal-oxide-semiconductor device with non-polar plane and AlN passivation layer Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084, China Applied Physics Letters http://dx.doi.org/10.1063/1.4971352

Utilizing a non-polar plane substrate and an ultra-thin AlN passivation layer results in significantly improved interface properties of a GaN metal-oxide-semiconductor (MOS) device. After depositing an Al2O3 gate dielectric layer on GaN substrates with polar c-plane and non-polar m-plane surfaces, it is found that the devices on the non-polar surface show much better interface properties than those on the polar surface. To further improve the interface properties, an amorphous ultra-thin AlN layer is deposited on the substrate before the Al2O3 deposition. The interface properties of both devices on the c-plane and m-plane are dramatically improved by the AlN passivation layer. The interface trap density of the Al/Al2O3/AlN/GaN MOS capacitor on the non-polar surface is reduced by two orders of magnitude compared to that on the polar surface. Local carrier recombination and associated dynamics in m-plane InGaN/GaN quantum wells probed by picosecond cathodoluminescence Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom Attolight AG, EPFL Innovation Park, Building D, CH-1015 Lausanne, Switzerland Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Applied Physics Letters http://dx.doi.org/10.1063/1.4971366

We report on spatially resolved and time-resolved cathodoluminescence (CL) studies of the recombination mechanisms of InGaN/GaN quantum wells (QWs) grown by metal-organic vapour phase epitaxy on bulk m-plane Ammono GaN substrates. As a result of the 2° miscut of the GaN substrate, the sample surface exhibits step bunches, where semi-polar QWs with a higher indium concentration than the planar m-plane QWs form during the QW growth. Spatially resolved time-integrated CL maps under both continuous and pulsed excitation show a broad emission band originating from the m-plane QWs and a distinct low energy emission originating from the semi-polar QWs at the step bunches. High resolution time-resolved CL maps reveal that when the m-QWs are excited well away from the step bunches the emission from the m-plane QWs decays with a time constant of 350 ps, whereas the emission originating semi-polar QWs decays with a longer time constant of 489 ps. The time constant of the decay from the semi-polar QWs is longer due to the separation of the carrier wavefunctions caused by the electric field across the semi-polar QWs. Smooth and selective photo-electrochemical etching of heavily doped GaN:Si using a mode-locked 355 nm microchip laser Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, U.S.A. Center for High Technology Materials, University of New Mexico, Albuquerque, NM 87106, U.S.A. Materials Department, University of California, Santa Barbara, CA 93106, U.S.A. Applied Physics Express http://dx.doi.org/10.7567/APEX.10.011001

We investigate the photo-electrochemical (PEC) etching of Si-doped GaN samples grown on nonpolar GaN substrates, using a KOH/K2S2O8 solution and illuminated by a Xe arc lamp or a Q-switched 355 nm laser. The etch rate with the arc lamp decreased as the doping concentration increased, and the etching stopped for concentrations above 7.7 × 1018 cm−3. The high peak intensity of the Q-switched laser extended the etchable concentration to 2.4 × 1019 cm−3, with an etch rate of 14 nm/min. Compositionally

http://dx.doi.org/10.1063/1.4971352http://dx.doi.org/10.1063/1.4971366http://dx.doi.org/10.7567/APEX.10.011001

KnowMade


selective etching was demonstrated, with an RMS surface roughness of 1.6 nm after etching down to an n-Al0.20Ga0.80N etch stop layer. Defects reduction in a-plane AlGaN epi-layers grown on r-plane sapphire substrates by metal organic chemical vapor deposition Advanced Photonics Center, Southeast University, Nanjing, Jiangsu 210096, China Applied Physics Express http://dx.doi.org/10.7567/APEX.10.011002

Nonpolar a-plane AlGaN epi-layers were grown on a semi-polar r-plane sapphire substrate with an innovative two-way pulsed-flows metal organic chemical vapor deposition growth technology. A root-mean-square value of 1.79 nm was achieved, and the relative light transmittance of the a-plane AlGaN epi-layer was enhanced by 36.9%. These results reveal that the innovative growth method is able to improve the surface morphology and reduce the defect density in nonpolar a-plane Al x Ga1– x N epi-layers, particularly those with an Al composition greater than 0.5, which are key materials for the fabrication of nonpolar AlGaN-based high light emission efficiency deep-ultraviolet light-emitting diodes.

OTHER (fundamental, material, characterization, equipment)

Information selected by Agnès Trassoudaine (Université d'Auvergne)

and Yvon Cordier (CRHEA-CNRS)

Triangular-shaped sapphire patterning for HVPE grown AlGaN layers Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany Institut für Physik, Humboldt Universität zu Berlin, 12489 Berlin, Germany Physica status solidi (a) http://dx.doi.org/10.1002/pssa.201600751

AlGaN growth by hydride vapor phase epitaxy on patterned sapphire substrates has been investigated. Growth on honeycomb-shaped holes is disturbed by parasitic growth of c-plane oriented AlGaN crystallites on n-plane sapphire facets. Triangular hole-like structures allow for

complete suppression of parasitic c-plane oriented AlGaN crystallites and coalescence of c-plane AlGaN at very low layer thickness. Additionally, triangular columnar sapphire patterns allow for biaxial strain relaxation and higher crystalline perfection. A total pressure of 400 hPa is favored for lateral overgrowth of ternary AlGaN by hydride vapor phase epitaxy. Lower pressures lead to strong composition inhomogeneity and higher pressure to lower crystal perfection. Additionally, very low V/III ratios of less than 10 yield best results. Lower ammonia supply support the growth of beneficial {11–22}-AlGaN crystallites on sapphire m-sidewalls which supresses undesired AlGaN growth on sapphire n-facets. Luminescence dynamics in AlGaN with AlN content of 20% Unité de Recherche sur les Hétéro-Epitaxies et Applications (URHEA), Faculté des Sciences, Université de Monastir, 5000 Monastir, Tunisia Physica status solidi (a) http://dx.doi.org/10.1002/pssa.201600481

Optical properties and carrier dynamics of an AlGaN layer with an AlN content of 20% have been studied using time-resolved photoluminescence (TR-PL). Despite the high density of defects due to the relatively high AlN content, an intense PL emission from the sample has been detected. Low-temperature PL spectra exhibit several features, accompanied by a strong emission-wavelength dependence of the PL decay time. A significant red-shift of more than 200 meV from the band edge is recorded for the PL emission from localized states. Temperature-dependent PL spectra of the sample are dominated by the emission from localized states and, furthermore, show a relatively slight decrease by almost an order of magnitude with increasing temperature from 45 to 300 K. Our observations indicate strong, spatial localization effects of carriers, resulting in an increase in the radiative recombination rate.

http://dx.doi.org/10.7567/APEX.10.011002http://dx.doi.org/10.1002/pssa.201600751http://dx.doi.org/10.1002/pssa.201600481

KnowMade


Morphologies and photoluminescence properties of GaN-based thin films grown on non-single-crystalline substrates Electrical and Electronic Engineering Course, Graduate School of Engineering Science, Akita University 1-1 Tegata-gakuen, Akita 010-8502, Japan Physica status solidi (c) http://dx.doi.org/10.1002/pssc.201600151

Morphologies and photoluminescence properties of gallium nitride-based thin films grown on non-single-crystalline substrates were investigated. The films were directly grown on quartz glass and amorphous-carbon-coated graphite substrates by a molecular beam epitaxy apparatus which has dual nitrogen plasma cells. Co-supplying of indium and gallium with simultaneous operation of the dual nitrogen plasma cells brought isolated and nano-pillar-shaped structures to the films. On the other hand, such structures were not obtained when the films were grown by the single plasma cell operation. Photoluminescence (PL) properties of the films greatly depended upon the morphologies. The intensities of the PL peaks emitted from the films which have such nano-pillar shaped structures were quite intense although the peak energies shifted to lower energy sides compared with those of the films grown by the single plasma cell operation. Ga-polar GaN film grown by MOVPE on cleaved ScAlMgO4 (0001) substrate with millimeter-scale wide terraces Institute for Materials Research, Tohoku University, Aoba-ku, 980-8577 Sendai, Japan Physica status solidi (a) http://dx.doi.org/10.1002/pssa.201600754

Cleaved ScAlMgO4 (SCAM) substrates with small lattice mismatch of 1.8% to GaN were used for metalorganic vapor phase epitaxial (MOVPE) growth of GaN. A single crystalline GaN film with a flat surface was obtained on a cleaved substrate without peeling off of the film, which is contrast to the growth on ZnO substrate with comparably small lattice mismatch to GaN. Polarity of the film was proven to be Ga polarity and an interface model was proposed based on the topmost surface structure of the cleaved SCAM. The effect

of substrate-cleaning and growth conditions on the surface morphology, crystallographic orientation relationship with the substrate, threading dislocation densities, small residual strains, and small background carrier density of GaN have been studied. To discuss the residual strains, thermal expansion coefficient of SCAM has also been measured. Properties of C-doped GaN Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, 39106 Magdeburg, Germany Physica status solidi (b) http://dx.doi.org/10.1002/pssb.201600708

Carbon-doping in the concentration range from [C] = 5 × 1017 to 1.2 × 1019 cm−3 is employed to achieve semi-insulating properties of GaN layers as required for electronic power devices. Using propane as a carbon precursor, an independent analysis of the carbon incorporation during growth and its impact on electrical properties of the layers was obtained as growth parameters for optimum GaN quality could be applied. We observe that C is within precision of measurements fully incorporated in GaN as compensating deep acceptor. In a series of Si + C co-doped samples, semi-insulating properties were obtained for [C] > [Si] and the compensation efficiency for electrons is around unity. Through the extrinsic C-doping technique previous ambiguous results on electrical and optical properties of GaN:C layers are clarified. Effect of the Ammonia Flow on the Formation of Microstructure Defects in GaN Layers Grown by High-Temperature Vapor Phase Epitaxy Institute of Materials ScienceTU Bergakademie FreibergFreibergGermany Institute of Nonferrous Metallurgy and Purest MaterialsTU Bergakademie FreibergFreibergGermany Institute of Applied PhysicsTU Bergakademie FreibergFreibergGermany Institute of Theoretical PhysicsTU Bergakademie FreibergFreibergGermany Journal of Electronic Materials http://dx.doi.org/10.1007/s11664-016-5204-z

http://dx.doi.org/10.1002/pssc.201600151http://dx.doi.org/10.1002/pssa.201600754http://dx.doi.org/10.1002/pssb.201600708http://dx.doi.org/10.1007/s11664-016-5204-z

KnowMade


High-temperature vapor phase epitaxy (HTVPE) is a physical vapor transport technology for a deposition of gallium nitride (GaN) layers. However, little is known about the influence of the deposition parameters on the microstructure of the layers. In order to fill this gap, the influence of the ammonia (NH3) flow applied during the HTVPE growth on the microstructure of the deposited GaN layers is investigated in this work. Although the HTVPE technology is intended to grow GaN layers on foreign substrates, the GaN layers under study were grown on GaN templates produced by metal organic vapor phase epitaxy in order to be able to separate the growth defects from the defects induced by the lattice misfit between the foreign substrate and the GaN layer. The microstructure of the layers is characterized by means of high-resolution x-ray diffraction (XRD), transmission electron microscopy and photoluminescence. In samples deposited at low ammonia flow, planar defects were detected, along which the nitrogen atoms are found to be substituted by impurity atoms. The interplay between these planar defects and the threading dislocations is discussed. A combination of XRD and micro-Raman spectroscopy reveals the presence of compressive residual stress in the samples. Simulation of real I-V characteristics of metal/GaN/AlGaN heterostructure based on the 12-EXT model of trap-assisted tunnelling Slovak University of Technology, Bratislava, Slovakia Ilmenau University of Technology, Ilmenau, Germany Applied Surface Science http://dx.doi.org/10.1016/j.apsusc.2016.06.120

The contribution employs electrical simulation to assess the effect of the distribution of aluminium in the metal/GaN/AlGaN heterostructure on the leakage current. The heterostructure is characterized by a high density of traps causing an increase of the leakage current consisting of the thermionic emission component and of a non-negligible contribution of trap-assisted tunnelling. The leakage current is highly sensitive to the bending of the potential barrier Ec in the subsurface region of the GaN/AlGaN structure. The band bending is strongly affected by the sheet

bound charge at the first GaN/AlGaN/GaN interface due to spontaneous and piezoelectric polarization. The overall charge depends on the concentration of Al, the distribution of Al at the first heterointerface having a strong effect on the formation of the potential barrier. Stability of AlGaN/GaN heterostructures after hydrogen plasma treatment Institute of Electrical Engineering SAV, Dúbravská cesta 9, 841 04 Bratislava, Slovakia Applied Surface Science http://dx.doi.org/10.1016/j.apsusc.2016.06.105

We report on the investigation of low temperature (300 °C) hydrogen plasma treatment influence on the AlGaN/GaN heterostructures. This issue was raised in the frame of study on processes related to hybrid integration of diamond with GaN-based devices. At the same time, the capabilities of thin SiNx covering were investigated. The samples were exposed to low pressure hydrogen plasma ignited in the linear plasma system at low temperature. We analyze the surface morphology of samples by scanning electron microscopy while microstructural changes down to AlGaN/GaN interface were studied using secondary ion mass spectrometry. The sheet resistance, monitored using circular transmission line measurements, increases more than 3.5 times after 60 min treatment. The basic transport properties of the fabricated circular high electron mobility transistors after H2 plasma treatment were analyzed. The sheet resistance increasing was attributed to the decrease of effective mobility. Whilst, the observed Schottky barrier lowering indicates necessity of gate contact protection. V-shaped pits in HVPE-grown GaN associated with columnar inversion domains originating from foreign particles of α-Si3N4 and graphitic carbon Graduate School of Science and Engineering, Yamaguchi University, Ube, Yamaguchi, 755-8611, Japan UBE Scientific Analysis Laboratory, Inc., Yamaguchi University, Ube, Yamaguchi, 755-0001, Japan

http://dx.doi.org/10.1016/j.apsusc.2016.06.120http://dx.doi.org/10.1016/j.apsusc.2016.06.105

KnowMade


Micron http://dx.doi.org/10.1016/j.micron.2016.11.008

The v-shaped pits (so-called V-pits) observed in hydride-vapor-phase-epitaxy-grown GaN and associated with the columnar inversion domains originating from foreign particles were investigated. The inversion domains on the front and back surfaces of the test sample were recognized after chemical mechanical polishing. It was found that the V-pits originate from the columnar inversion domains. The inversion domains, in turn, arise from the particles that exist on a low-temperature GaN buffer layer on sapphire substrate. Using transmission electron microscopy, these particles were found to be of α-Si3N4 and graphitic carbon. Such particles are attributable to the components of the reactor and adhere to the low-temperature GaN buffer layer, which has a surface roughness of the order of several nanometers. Thus, an effective way of obtaining HVPE-grown thick GaN layers without the V-pits associated with columnar IDs is to maintain the parts of the HVPE chamber properly to prevent foreign partic

III-N Technology€¦ · business development by helping them to understand their IP environment...

Documents

Transcript of III-N Technology€¦ · business development by helping them to understand their IP environment...