Boron Nitride and graphene nanostructures: properties and ...

Boron Nitride and graphene nanostructures: properties and applications NanoCenter Seminar, Pittsburgh 17th March 2009

NanoBio Spectroscopy Group, Dpto. Física de Materiales, Universidad del País Vasco,

Centro Mixto CSICUPV/EHU and DIPC Edificio Korta, San Sebastián, Spain

http://nanobio.ehu.es Email: [email protected]

Angel Rubio

Boron Nitride and graphene nanostructures: properties and applications


OUTLINE● Introduction to BN and other inorganic nanotubes● Structural, mechanical and Electronic properties:

doping , what is the bandgap of BN tubes? ● Optical absorption of the single BNsheet and

BNnanotubes (Abinitio calculations including manybody corrections (GW + BetheSalpeter)

● Luminiscence + Electric field effects (devices)● Graphene/Graphite● Conclusions


●Density functional theory in the ( LDA)Local Density Approximation or beyond●Plane wave or realspace grid expansion●Pseudopotentials and Supercell geometry●MBPT and TDDFT+ RPA Response Calculations●Perturbation DFT theory for phonons

First-principle calculations: Technical Details


Layered Materials

MoS2

WS2

NbS2

TaS2

VS2

ReS2

WSe2

MoSe2

Graphite

ChalcogenidesCarbon Nitride

Boron Nitride

OTHERS VO5, NiCl2 MgB2

Boron CarbonNitride......and your imagination!!!!

Superconductors, work together with Hardy Gross group, FU-Berlin


Layered Materials

Carbon Nanotubes

MoS2 Nanotubes

BN nanotubes

Fullerenes

BN cages

MoS2 cages


AR, Y. Miyamoto, S.G. Louie, and M.L. Cohen PRB (2004, 2005)

Composite NANOTUBES: stability


Abinitio prediction of nanotubes: laminar bulk phase”

C: metal/semiconductor depending on chirality. Luttinger liquid,

superconductivity, mechanical strenght, etc.....

BN: wide band gap semiconductor; conduction band bottom NFE;

mechanic resistance, field emission, piezoelectricity

BC3: small gap; wallwall induced � conductivity

BC2N: variety of chiral structures; nanocoils”

B: metallic (B/Ndoped Ctubes: stochastic heterostructures)

Synthesized in small quantities (besides BN)

Other inorganic tubes: CxNy; MgB2, (MoS2 family, R. Tenne et al)

Work with Y. Miyamoto, X. Blase, S.G. Louie, M.L. Cohen, V. Crespi (BxCyNz)

with I. Boustani and J.A. Alonso (Boron) http://nano-bio.ehu.es

http://nano-bio.ehu.es/


Interest for BN nanotubesStability of BN nanotubes predicted in 1994

(AR , J. Corkill, X. Blase, M.L. Cohen, S.G. Louie, PRB 1994)

First production of multi-wall BN-nanotubes in 1995

(Chopra et al., Science (1995))

Properties predicted to be alternative to those of C-tubes :

large band gap independent of helicity and number of tubewalls

free electron state located inside the tube (conduction bandbottom) dipolar layer at the tube surface, buckling Quantum polarization: Piezoelectricity low chemical reactivity

Properties similar to those of Ctubes:high Young modulus

Potential applications electromechanical devices, field emitters, field effect transistors


~1/r

Buckling of geometry optimized BNtubes:

dipolar shell structure

intertube interaction


0

L. Vaccarini, C. Goze, L. Henrard, E. Hernández, A. Loiseau, P. Bernier and A.R Carbon (2000);Phys Rev. Lett. (1998); Appl.Phys. A (1999)

Mechanical properties


BN single wallnanotubes

R.S. Lee et al PRB64, 121405 (2001); Courtesy of A. Loiseau


200 nm

5 nm

Production of SW-BN-tubes• mostly single wall• ropes and isolated• diameter: 10 -20 Å• mostly zigzag tubes• length: 100300 nm

R.S. Lee et al PRB64, 121405 (2001); Courtesy of A. Loiseau

Mass production of double wall BN tubesJ. Cumings and A.Zettl, CPL (2000)


Bandstructure (LDA)

Graphine-layer BN-sheet

(transparent)(black)

N

B


Bandstructure (LDA)role of stacking....interlayer interaction

Graphite AB-stacking h-BN


Controversy about outofplane modes weakbonding????

Vibrational Properties: Raman and IR spectroscopy


Phonons in graphite:

Review by L. Wirtz and AR, Solid State Comm. (2004)


Vibrational Properties: Raman and IR spectroscopy

PRL 98 (2007) (IXS experiments in Grenoble)


Electronic structure of BNtubes: (LDA)

Uniform band gap, no metallic BNtubes!

AR, X. Blase, M. L. Cohen, S. G. Louie PRB (1994,95); Euro. Phys. Lett (1994)


BN(4,4) metallic doping: superconductivity?

AR, Y. Miyamoto, S.G. Louie, M.L. Cohen PRB53, 4023 (1996)


The problem of Band Gap in nanotubesis related to the one of bulk hBN

How much is the band gap in hBN?

?


Optical Absorption/Emission Spectroscopy

x

optical gap ≠ photoemision (QP) gap

structural characterisation Role of packing: tubetube interaction


Beyond DFT

Bethe-Salpeter eqn:

Im [] ~ vc

|<v|D|c>|2 (Ec-E

v-)

Im [] ~ s |

vc<v|D|c>A

vcS|2 (S)


A.G. Marinopoulus, L. Reining, A. Rubio (unpublished 2002)

Optical Properties of CTubes: A way to elucidate tubechiralityZeolite type AlPo

4-5

N. Wang et al, Nature 408, 51 (2000)

CandidatesC(3,3)C(5,0)C(4,2)

Z.M..Lie et al, PRL (2001)

Depolarisationeffects

Marinopoulus, Reining, A.R. PRL /03), PEB(08)

Bound excitons in bulk h-BN

Experiment: Tarrio and Schnatterly, PRB 40, 7852 (1989) equally: Lauret et al PRL

Bound excitons in bulk h-BN

energy broadening: 0.1 eV

Fine structure of spectrum

B. Arnaud et al, PRL 96 (2006)Inset: comparison with absorption of K. Watanabe et al, Nature Materials (2004)

excitonic wave-functionhole on top of a N atom

Fine structure of spectrum

single excitonic peak(doubly degenerate exciton)

dark excitonic state(doubly degenerate)


BN nanotubes Dimensionality effect: Exciton in (quasi-) 1-D, 2-D, 3-D

L. Wirtz, A. Marini, AR PRL (2006)

Depolarisation effects as in C tubes


Park, Spataru, Louie PRL (2006)Wirt, Marini, Rubio PRL (2006)

Exciton localisation in C and BN nanotubes

Frenkel

UV light

High Luminiscence yield in BN!!!

IR light


Is there any experimental evidence of

such large excitonic effects?


e

EELS experiments on isolated BN nanotubes


Evidence for ultraviolet lasing of hexBN single crystal

K. Watanabe, T. Taniguchi, and H. Kanda, Nat. Mater. 3, 404 (2004)

http://link.aip.org/link/?&l_creator=getabs-normal&l_dir=FWD&l_rel=CITES&from_key=PRLTAO000096000012126104000001&from_keyType=CVIPS&from_loc=AIP&to_j=NMAACR&to_v=3&to_p=404&to_loc=DOI&to_url=http://dx.doi.org/10.1038/nmat1134


Luminescence origin: due to electronholerecombination on defects?

Carbon substitution of a Nitrogenacceptor impurity

The most probably candidates are: (Dislocations)?

Nitrogen vacancydonor impurity


The problem:valence and conduction orbitals are strongly modified

by the presence of an impurity

4

The highest three occupied orbitalsin the pure sheet (right) and with a carbon impurity in a 6x6 supercell


A high concentration of defects modifies the exciton peak in the single hex BN layer

Optical absorption within BSE approximation

GAP

6.1 eV

Optical absorption within RPA approximation

Defects/exciton states (shallow and deep) dominate the luminiscence below 6 eV; The main absorption peak of BN is at 6.1 eV ( this provides a coherent description of EELS , optics and luminescence)

Main absorption peak


Towards optoelectronic devices: role of

perpendicular E-field

ROLE of DEFECTS?

C. Attacalite, L. Wirtz, A. Marini and AR (in progress)


No control of absorption/luminescence in Pure BN tubes


(RPA) spectrum of (9,9) BN tube with defects

with defectE = + 0.02V/Å

with defectE = 0.02V/Å

with defectE = 0

without defectE = 0

=> Defect state moves with respect to valence and conduction band!

=> possible influence on the photoluminescence!


Transverse Electric Field in BN: control blue/UV Light emission ?

Through Defects


GRAPHITE / GRAPHENE

recent work on ARPES, correlation effects and

electron-phonon coupling

Exp (T.Pichler group, U Wien, Austria)

D. C. Elias et al., Science 323, 610 -613 (2009)

Ongoing work:optics of hydrogenated graphene: graphAne

GAP ~ 5.4 eV


Electron-electron correlations


Electron-electron and e-phonon coupling


Electron-electron and e-phonon couplingKohn-anomaly in graphite

Lazari, Mauri PRL (2004); exp J, Maultzsch, et al PRL(2004)


Phonon dispersion close to KIn spite of the general good agreement the

situation is not clear close to KK


Phonon dispersion close to K


Electron-electron and e-phonon coupling


K K'

{ℏq

{

q

Raman Dline

dispersive


Raman Dline


The case of Doped Graphene

Therefore the effective interaction felt by the electrons starts to be weaker due

the stronger screening of the Coulomb potential.

With doping graphene evolves from a semimetal to a real metal.

http://arxiv.org/abs/0808.0786

http://arxiv.org/abs/0808.0786


Electronphonon Coupling at KLDA results is recovered in doping graphene


Summary ●BN alternative material to C tubes for nanoelectronic applications

●Compatible with C; add to the nano-lego

●Optical-devices: luminiscence tunable by the applied perpendicular E-field (high efficiency); excitonic effects important

●Work on chemical synthesis: large scale production

MORE to come in the near future..................


Acknowledgements

http://www.etsf.es

S.G. Louie, M.L. Cohen and A. Zettl, Y. Miyamoto (NEC)Department of Physics, University of California at Berkeley, USA

Andrea MariniIstituto Nazionale per la Fisica della Materia e Dipartimento di Fisica

dell'Università di Roma ``Tor Vergata'', Roma, Italy

Ludger Wirtz, Francesco Mauri and Claudio Attacalite

CNRS, France

J. Serrano (ESRF Grenoble) T. Pichler (IW F Dresden)


For more details see: http://nano-bio.ehu.es

Than

k yo

u!!!!

Boron Nitride and graphene nanostructures: properties and ...

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