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Composition and Carrier Concentration Dependence of the Electronic Structure of InyGa1-yAs1-xNx Films With Nitrogen Mole Fraction Less Than 0.012



Youn S. Kang, Lawrence H. Robins, Anthony Birdwell, Alexander J. Shapiro, W. R. Thurber, Mark D. Vaudin, M M. Fahmi, D Bryson, S N. Mohammad


The electronic structure of Si-doped InyGa1-yAs1-xNx films on GaAs substrates, grown bynitrogen-plasma-assisted molecular-beam epitaxy, was examined by photoreflectance PR spectroscopy at temperatures between 20 and 300 K. The films were approximately 0.5 m thickand had nitrogen mole fraction between x=0.0014 and x=0.012, measured indirectly by asecondary-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 2 1016 and 1.1 1018 cm-3, measured by Hall effect. Three critical-point transitions were identifiedby PR: the fundamental band gap highest valence band to the lowest conduction band ; thespin-orbit split valence band to the lowest conduction band; and the highest valence band to anitrogen impurity band above the lowest conduction band . The measured critical-point energieswere described by a band anticrossing BAC model with the addition of a Burstein-Mossband-filling term. The fitted BAC parameters were similar to previously reported values. The Nimpurity level was located 0.3004 0.0101 eV above the conduction-band edge at 20 K and0.3286 0.0089 eV above the conduction-band edge at 295 K. The BAC interaction parameter was2.588 0.071 eV. From the small magnitude of the Burstein-Moss energy shift with increasingcarrier concentration, it was inferred that the carrier concentration probed by PR is reduced from thebulk Hall-effect carrier concentration by a reduction factor of 0.266 0.145. The PR linesbroadened with increasing carrier concentration; the line broadening tracked the predictedBurstein-Moss energy shift for the bulk carrier concentration. The surface-normal lattice constantsof the films were measured by x-ray diffraction. Comparison of the measured lattice constants withVegard s law showed the presence of tensile strain in the surface-normal direction with magnitudebetween 1.5 10-3 and 3.0 10-3. The effect of strain on the PR energies was too small toobserve.
Journal of Applied Physics


band anti-crossing model, band structure, Burstein-Moss effect, compound semiconductors, Hall effect, photoreflectance, x-ray diffraction


Kang, Y. , Robins, L. , Birdwell, A. , Shapiro, A. , Thurber, W. , Vaudin, M. , Fahmi, M. , Bryson, D. and Mohammad, S. (2005), Composition and Carrier Concentration Dependence of the Electronic Structure of InyGa1-yAs1-xNx Films With Nitrogen Mole Fraction Less Than 0.012, Journal of Applied Physics (Accessed May 26, 2024)


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Created November 1, 2005, Updated February 19, 2017