Composition and carrier-concentration dependence of the electronic structure of In{sub y}Ga{sub 1-y}As{sub 1-x}N{sub x} films with nitrogen mole fraction of less than 0.012

Journal Article · Tue Nov 01 00:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2127126· OSTI ID:20719663

Kang, Youn-Seon; Robins, Lawrence H; Birdwell, Anthony G; Shapiro, Alexander J; Thurber, W Robert; Vaudin, Mark D; Fahmi, M M.E.; Bryson, Damian; Mohammad, S Noor ^[1]

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1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

The electronic structure of Si-doped In{sub y}Ga{sub 1-y}As{sub 1-x}N{sub x} films on GaAs substrates, grown by nitrogen-plasma-assisted molecular-beam epitaxy, was examined by photoreflectance (PR) spectroscopy at temperatures between 20 and 300 K. The films were approximately 0.5 {mu}m thick and had nitrogen mole fraction between x=0.0014 and x=0.012, measured indirectly by a secondary-ion-mass spectrometry calibration; indium mole fraction between y=0.052 and y=0.075, measured by electron-dispersive x-ray spectroscopy; and carrier concentration between 2x10{sup 16} and 1.1x10{sup 18} cm{sup -3}, measured by Hall effect. Three critical-point transitions were identified by PR: the fundamental band gap (highest valence band to the lowest conduction band); the spin-orbit split valence band to the lowest conduction band; and the highest valence band to a nitrogen impurity band (above the lowest conduction band). The measured critical-point energies were described by a band anticrossing (BAC) model with the addition of a Burstein-Moss band-filling term. The fitted BAC parameters were similar to previously reported values. The N impurity level was located 0.3004{+-}0.0101 eV above the conduction-band edge at 20 K and 0.3286{+-}0.0089 eV above the conduction-band edge at 295 K. The BAC interaction parameter was 2.588{+-}0.071 eV. From the small magnitude of the Burstein-Moss energy shift with increasing carrier concentration, it was inferred that the carrier concentration probed by PR is reduced from the bulk (Hall-effect) carrier concentration by a reduction factor of 0.266{+-}0.145. The PR lines broadened with increasing carrier concentration; the line broadening tracked the predicted Burstein-Moss energy shift for the bulk carrier concentration. The surface-normal lattice constants of the films were measured by x-ray diffraction. Comparison of the measured lattice constants with Vegard's law showed the presence of tensile strain (in the surface-normal direction) with magnitude between 1.5x10{sup -3} and 3.0x10{sup -3}. The effect of strain on the PR energies was too small to observe.

• OSTI ID: 20719663
• Journal Information: Journal of Applied Physics, Vol. 98, Issue 9; Other Information: DOI: 10.1063/1.2127126; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALIBRATION
CARRIER DENSITY
DOPED MATERIALS
ELECTRONIC STRUCTURE
ENERGY GAP
GALLIUM ARSENIDES
GALLIUM NITRIDES
HALL EFFECT
INDIUM NITRIDES
ION MICROPROBE ANALYSIS
L-S COUPLING
LATTICE PARAMETERS
LINE BROADENING
MASS SPECTROSCOPY
MOLECULAR BEAM EPITAXY
NITROGEN
SEMICONDUCTOR MATERIALS
SILICON
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY