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Silicon and III-V Compounds for Detectors – Technology and Characterisation at ITME

R. Kozlowski, Z. Luczynski and E. Nossarzewska-Orlowska

1st RD50 Workshop

(CERN, October 2-4, 2002)

Institute of Electronic Materials Technology, Warsaw, Polandwww.itme.edu.pl

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Plan of presentation

• short characteristic of ITME

• materials for detectors:

- silicon (bulk and epitaxial)

- III-V compounds (SI GaAs, SI InP and MOCVD III-V including GaN layers)

• materials characterisation methods

1st RD50 Workshop

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1st RD50 Workshop

The Institute consists of the following divisions:

• Department of Silicon Technology• Silicon Epitaxy Laboratory • Department of Semiconductor Compounds Technology• III-V Materials Epitaxy Laboratory• Department of III-V Materials Applications• Department of Oxide Single Crystals Technology• Department of Ceramics and Seals Technology• Laser Laboratory• Glass Laboratory• Department of Thick Films Technology• Department of Piezoelectronics• Laboratory of Characterization of High Purity Materials• Department of Microstructural Analyses

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1st RD50 Workshop

Czochralski silicon crystals

Orientations <111>, <100> and <110>Carbon content: max. 0.5 ppmOxygen content: controlled level in the range of 24-38 ppm

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1st RD50 Workshop

Silicon wafers -as cut, lapped, etched and polished

Available resources:• Thermal donors annealing furnace,• Silicon oxidation furnace (quartz tube up to 8”)

• Diameter: 76 mm, 100 mm, 125 mm, 150 mm (6”),• Orientation: <111>, <100> and <110>,• One-side or double-side polished,• Thin double-side polished wafers (down to 50 µm)

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1st RD50 Workshop

Float Zone silicon crystals

• diameter: 2”• orientation: <111> or <100>• doping:

- p-type: boron- n-type: phosphorus

• resistivity range:- boron: 20 - 300 Ωcm- phosphorus: 6 - 200 Ωcm

FZ silicon doped with different impurities for research purposes (Sn, O).

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1st RD50 Workshop

Magnetic CZ puller*

• Better homogenity of the dope in axial and radial direction• Minimum available oxygen concentration: ~3x1017 at/cm3.

Magnet - 5000 GaussCharge capacity of the above: 30 kgDiameter of pulling crystals: 100 mmCable pulling system:Max pulling stroke: 1350 mm Seed pulling speed: 0.2 - 6.0 mm/minThe full automatic crystal growing control system.

* pulling will start in the beginning of 2003

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1st RD50 Workshop

Si:Ga crystals (1)

Parameters of Ga doped silicon crystal:

Diameter – 3”Type – pResistivity – (0.5 –2.0) Ωcm[Ga] – (4x1016 – 7x1015) cm-3

[O] – 6.5x1017 cm-3

[C] < 5x1015 cm-3

The life time of minority carriers - 25÷30 µs.

A new generation of crystalline silicon solar cells

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Si:Ga crystals (2)1st RD50 Workshop

200 300 400 500 600

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0200 300 400 500 600

0.0

0.2

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0.8

1.0

1.2

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1.6

1.8

2.0

8-G

a6-G

a

4A+4B-Ga

3-G

a

B,P

1-Ga

T=11KA

bs. c

oeff.

(cm

-1)

Wavenumber (cm-1)

The absorption spectrum (FTIR) of Si:Ga related to the transition from the ground state to the exited states of gallium.

Line notification according to the paper: A.Onton et all., Phys.Rev. V 163 No 3, (1967), 685.

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Silicon epitaxial layers (1)1st RD50 Workshop

Epi-layer on substrates of diameter: 2”, 3”, 4”, 5”, 6” (CEMAT-Silicon)

Type n - phosphorus dopedType p - boron dopedThickness range: 1÷ 200 µmResistivity range: 0.01 ÷ 1000 ΩcmSingle layers and multi-layers structures

Characterization:thickness by IR reflectance spectrometry resistivity by: C-V method with Hg probe; spreading resistance(resistivity profile on a bevel), 4-points probe

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1st RD50 Workshop

Silicon epitaxial layers (2)

Epitaxial layer thickness map measured on BIO-RAD spectrometer

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1st RD50 Workshop

Silicon epitaxial layers (3)

Resistivity profile measured by SR method for high-resistivity

silicon epitaxial layer

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

0 10 20 30 40 50 60 70

micrometers

ohm

cm

Schematic view ofsilicon ball detector

A. Kordyasz et al..Nucl. Instr. andMeth. in Phys. Res A 390 (1997)

198-202

4π epitaxial Si detectors array for in-beam spectroscopy experiments

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Silicon epitaxial layers (4)Perspective material for thin silicon detectors

Resistivity profile of 50 µm, 50 Ωcm epitaxial layer

0.01

0.1

1

10

100

1000

0 20 40 60

w [ µm ]

Ro

[ o

hm

cm ]

Idea: the depletion voltage might stay constant up to very large fluences!

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Silicon epitaxial layers (5)1st RD50 Workshop

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

0 20 40 60 80 100

Thickness in depth [µm]

Res

isti

vity

[oh

mcm

]

Type "n"Type "p"

Epitaxial structure of integrated telescope E+∆E for identification of light charged particles and heavy ionsin nuclear and heavy ions physics

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III-V compounds (1)

GaAsØgrown by Czochralski (LEC) method (low and high-pressure)Ødiameter 2", 3" and 4", orientation <100> or <111>Øn-type : Te, Sn or Si (n=1017....1019 cm-3)Øp-type : Zn (n=1017....1019 cm-3)ØSemi-Insulating : undoped (µ > 6×103 cm2/Vs, ρ > 107 Ωcm).

InPØgrown by Czochralski (LEC) method Ødiameter 2", orientation <100> or <111>Øn-type : undoped (n=5×1015..1×1016cm-3)Øn-type : S, Sn (n=2×1017..1×1019cm-3)Øp-type : Zn (p=5×1017..1×1019cm-3)ØSemi-Insulating : Fe (µ > 2 x 103 cm2/Vs, ρ > 107 Ωcm )

Ingots

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1st RD50 Workshop

III-V compounds (2)

Simplified structure of α particle detector based on SI GaAs or SI InP substrate

SI GaAs crystal parameters: µ>6000 cm2/Vs, ND<1015 cm-3, EPD<5x104 cm-2, homogeneity

The α particle detector

d = 100 µm

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1st RD50 Workshop

III-V compounds (3)

(a) (b)Spectra of α (228 Th) particle detected by SI GaAs detector. (a) structure illuminated from Schottky barrier side,(b) structure illuminated from ohmic contact side

The α particle detector

U=350 V U=350 V

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1st RD50 Workshop

III-V compounds (4)

Charge collection efficiency for α- 5.48 MeV as a function of bias voltage for SI GaAs detector

0 100 200 300 400 500 6000

10

20

30

40

50

60

70

80

90

100

Cha

rge

Col

lect

ion

Effi

cien

cy

[%]

U [V]

The α particle detector

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III-V Materials Epitaxy Laboratory

1st RD50 Workshop

The growth of structures applying binary, ternary and quaternary compounds related to GaAs, InP

and GaN

EPITAXIAL LAYER THICKNESS:* from 1ML to 15µm;* radial thickness variation on the wafer: in the range of 1ML.

The following methods are used for the characterisation of layers:ØX-ray;ØPhotoluminescence;ØHall method;ØC-V profile with electrochemical etching;ØAtomic Force Microscopy.

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1st RD50 Workshop

LP MOVPE - Low Pressure Metalorganic Vapor Phase Epitaxy

AXT 200 systemP=20÷100 mbarT= 650-700 oC

as III group elements:TMGa - trimethylgallium,TMIn - trimethylindium,TMAl - trimethylalumininum

as V group elements:AsH3 - arsinePH3 - phosphine

In Ga A P (=1,05(m (GRIN) d=80nm

In Ga A P (?=1,05?m) Si:7x10 cm (GRIN) d=80nm InP Si:3x10 cm ( buffer) d=1 ?m

InP n-type substrate

In Ga A P (?=1,18?m) Si:7x10 cm (GRIN) d=50nm In Ga A P (?=1,26?m) (barrier) d=12nm In Ga As (?=1,64?m) (active QW layer) d=8,5nm In Ga A P (?=1,26?m) (barrier) d=12nm In Ga A P (?=1,18?m) (GRIN) d=50nm

InP Zn:7x10 cm ( upper clading) d=500nm In Ga A P (?=1,05?m) (GRIN) d=80nm

In Ga A P (?=1,18?m) Zn:2x10 cm (contact) d=50nm In Ga As (?=1,64?m) Zn: 2x10 cm ( contact) d=100nm

Quantum well laser structure

as dopant:DMZn -dimethylzinkSiH4 - silane

Epitaxial layers: InP, GaAsand related materials

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LP MOVPE - Low Pressure Metalorganic Vapor Phase Epitaxy

AXT 200/4 RF-S systemP=100÷300 mbar

T= 1200 oC

as III group elements:TMGa - trimethylgallium,TMIn - trimethylindium,TMAl - trimethylalumininum

as V group elements:NH3 - ammonia

as dopant:Cp2MgSiH4

Epitaxial layers: GaN, AlN, AlGaN, InGaN

Applications: LEDs, HEMTs, lasers, photodetectors

Substrates: sapphire, NGO, Si, SiC and GaN (homoepitaxy)

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1st RD50 Workshop

Substrate materials for GaN at ITME

MIXED PEROVSKITE − (La, Sr) (Al, Ta) O3 − LSATØCrystal system: regular (mixed

perovskite)Ø Lattice constant: a = 7.735 ÅØ Lattice mismatch: ∆ < 1%

NEODYMIUM GALLATE − NdGaO3Ø Crystal system: orthorombicØ Lattice constants: a = 5.4276 Å

b = 5.4979Åc = 7.7078Å

Ø Lattice mismatch : ∆ ~ 0,7% (101)

SAPPHIRE − Al2O3Ø Crystal system: trigonalØ Lattice constants: a = b = 4.7589 Å

c = 12.991 ÅØ Lattice mismatch: ∆ ∼14%

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1st RD50 Workshop

Processing department and mask laboratory (1)Technological line consists of:• deep UV optical lithography (0.5µm smallest feature size), • reactive ion etching (RIE) technique (and ICP type of RIE), • plasma enhancement chemical vapour deposition reactor(PECVD),

• RF/DC sputtering unit,• Rapid Thermal Annealing (RTA),• Ion Implantation.

Deposition of:• dielectrics ( Si3N4 SiO2, Al2O3, Y2O3),• semiconductors (AlN, GaN), • multilayer metal sandwiches.

Chromium masks on up to 7” substrates (smallest line width of 0.5µm)

Devices with sub micrometer geometry approaching quantum regime of operation (using e-beam writer).

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1st RD50 Workshop

Electron-Beam lithography

Main fields of applications:

• fabrication of master masks and reticles for contact, proximity and projection lithography, especially for large area structures, like nuclear radiation detectorsor SAW filters and resonators

• direct exposure of semiconductor wafers, especially to be used in the sub-0.5-micrometer range (e.g. monolithic microwave integrated circuits, diffractive optical elements)

Processing department and mask laboratory (2)

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1st RD50 Workshop

Electron-Beam lithography• high resolution and quality

Split gate 0.07 µmLift-off metallization Au/Cr 0.1 µm

Submicron strip structureLift-off metallization, line width 0.8 µm

• special 3D structures

The 0.2 µm footprint T-shaped gateLift-off metallization Au/Cr 0.4 µm

Central part of the 8-phase-levelFresnel microlens

Processing department and mask laboratory (3)

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1st RD50 Workshop

Sensor of ultraviolet radiation on Gallium Nitride

• Absorption edge - 365 nm.• Detector exhibits high sensitivity only in the UV

range without applying expensive optical filters.• Sensitivity is 3 orders of magnitude lower for

visible light.

Processing department and mask laboratory (3)

280 300 320 340 360 380 400 420 440 4601E-4

1E-3

0.01

0.1

curr

ent s

ensi

tivity

( A

/ W

)

wavelenght ( nm )

Øactive surface 0.8 mm

Øcurrent sensitivity > 0.07 A/W

Ødetectivity D > 109 cm Hz1/2/W

Ødynamic resistivity (U = 0) 10 GΩ

ØUV/visible light rejection ratio > 103

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1st RD50 Workshop

• C-V and S-R,

• FTIR spectrometer,

• photoluminescence,

• SIMS (Cameca IMS 6F)

• electron micro-probe analysis (Cameca SX100),

• HRPITS and C-DLTS,

• ESR

Materials characterisation methods at ITME:

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1st RD50 Workshop1st RD50 Workshop

SIMS

SIMS profile of O-concentration for silicon sample,O-diffusion: 16 hrs at 1150 oC

(Measurement on bevelled sample)

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1st RD50 Workshop

ESR

ESR spectra of Mn2+ in GaN crystal

220 240 260 280 300 320 340 360 380 400 420 440 460

band X, T = 6 K

GaN: MnH || c

ES

R s

igna

l [ar

b.u.

]

magnetic field [mT]

In GaN crystals Mn2+ have 3d5 electron configuration wit S=5/2. Therefore in EPR spectra we observe 5 fine structure lines. Each of them is splitted on six components. This splitting is caused by hiperfine interaction between electron spin and magnetic nucleus 55Mn with nuclear spin I=5/2

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1st RD50 Workshop

700 800 900 1000 1100 1200 1300

0.6

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1.4

1.6700 800 900 1000 1100 1200 1300

0.6

0.8

1.0

1.2

1.4

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TDD

3

VnO

m

TDD

3

VO

3

VO

2

b)VO

3

1225

VO

3TD

D3

a)

OiT=300K

Abs

orpt

ion

coef

ficie

nt (

cm-1

)

Wavenumber (cm-1)10

12TD

D3

The local vibration modes of VnOn defects in:a) neutron irradiated with dose 6x1016n/cm2; b) non-irradiated silicon after annealing at 600 oC

FTIR

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Summary1st RD50 Workshop

• ITME activities in silicon technology were exemplified trough the wide range of parameters of silicon ingots, wafers and epitaxial layers.

• Research and development works in the field of III-V compounds comprise the growth of bulk crystals (in particular SI GaAs and SI InP) and deposition of multilayered structures.

• ITME recent activities in technology of wide-bandgapmaterials are related both with the preparation of substrates and MOCVD epitaxial growth of GaN structures.

• The ITME facilities for fabrication of semiconductor devices and materials characterisation were also outlined.