The Narrow Energy Gap The Narrow Energy Gap

Dilute Nitride Alloy Dilute Nitride Alloy

In(AsN)In(AsN)

A. Patanè, O. Makarovsky, W.H.M. Feu, L. Eaves School of Physics and AstronomyThe University of Nottingham, UK

CollaboratorsCollaborators A. Krier and Q. Zhuang

Physics Department, Un. of Lancaster, UK

R. AireyEPSRC Facility for III-Vs, Un. of Sheffield, UK

O. Dravchenko and M. Helm

Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, GermanyEU High Magnetic Field Labs, http://www.ru.nl/hfml

http://www.nottingham.ac.uk/~ppzphy17/http://www.nottingham.ac.uk/~ppzphy17/

“Trends in the electronic structure of dilute nitride alloys”E.P. O’Reilly et al., SST 24 033001 (2009)

The band structure of III-V-Ns is determined by the distribution of energy levels due to N-impurities and N-clusters and their hybridization with the extended CB states.

GaAsN InPN InAsN

N-levelN-levelCBECBE

0.2 eV 0.4 eV

E = 1 eV

N-pairs and clustersN-pairs and clusters

Comparing III-N-VsComparing III-N-Vs

“Theory of the electronic structure…”A. Zunger et al., PRB 64 115208 (2001)

Electron localization occurs if the CBE of the dilute ‘‘impurity’’ species lies below that of the host III-V, and the impurity electron mass, me, is heavy.

GaN GaAs InN InAs

0.3 eV

mmee=0.13mo

0.02mo

N

CBECBE

GaAsGaAsNN InAsInAsNN

Electron massElectron mass

Comparing III-N-VsComparing III-N-Vs

This workThis work

• Tuning the band gapTuning the band gap• Electron mobility and cyclotron massElectron mobility and cyclotron mass• Electron coherence length Electron coherence length • Hot electron dynamicsHot electron dynamics

Probing electronic properties

De la Mare et al., APL 95, 031110 ‘09De la Mare et al., APL 95, 031110 ‘09

3.0 3.5 4.0

(m)

0% x=1%

PL

(arb

. un

its)

T = 4.2K

• Admixing of the N-levels with the band states of the III-V shifts the PL emission to longer >3m

• A large relative change of the band gap energy, Eg:

-Eg/Eg >10% at x=1%

• Prospects for IR gas sensing, security applications, lasers…

InAsN for IR-OptoelectronicsInAsN for IR-Optoelectronics

InAs1-xNx on GaAs grown by MBE

Kudrawiec Kudrawiec et al. APL 94, et al. APL 94, 151902 ’09151902 ’09J. Misiewicz (Wroclaw Un., Poland)

De la Mare et al., APL 95, 031110 ‘09De la Mare et al., APL 95, 031110 ‘09

3.0 3.5 4.0

(m)

0% x=1%

PL

(arb

. un

its)

T = 4.2K

• Admixing of the N-levels with the band states of the III-V shifts the PL emission to longer >3m

• A large relative change of the band gap energy, Eg:

-Eg/Eg >10% at x=1%

• Prospects for IR gas sensing, security applications, lasers…

InAsN for IR-OptoelectronicsInAsN for IR-Optoelectronics

x=1%

InAs1-xNx on GaAs grown by MBE

TEM, R. Beanland (UK)

0.0 0.4 0.8 1.2 1.6100

1000

10000

100000

(c

m2 V

-1s-1

)

x (%)

T = 293 K

Hall MobilityHall Mobility

InAsN

Patanè et al. APL 93 252106 ’08

• Nitrogen reduces the electron mobility.

GaAsN

• is limited by electron scattering by N-atoms, -pairs and–clusters. These effects are stronger in GaAsN than in InAsN due to the vicinity of the N-related states to the CBE.

• Model for GaAsN predicts a strong reduction of the mobility and electron mean free path due to the N-levels.

Fahy et al. PRB 74, 035203 ‘06

GaAsN

Electron Cyclotron MassElectron Cyclotron Mass

c*e 2/eBm

0 2 4 6 8 10

Tra

nsm

issi

on (

arb.

unit

s)

B (T)

ee mm 025.0*

ee mm 027.0*

ee mm 060.0*

ps15.0~e

ps10.e

x=0%

0.4%

1.0%

ee mm 029.0*

ps1.0~e

0.6%

T =100 K= 2.9THz

ps20.0~e

The cyclotron mass increases with increasing x.

Comparing the N-induced change of the mass in InAsN and GaAsN.

Patanè et al. PRB 80 115207 ’09

(me)

GaAsN LCINS, O’Reilly

CR InAsN

CR/PR GaAsN

InAs1-xNx