Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 42: GaN: devices
HL 42.6: Vortrag
Donnerstag, 29. März 2007, 15:15–15:30, H13
Band gap and band parameters of InN from quasiparticle energy calculations based on exact-exchange density-functional theory — Patrick Rinke1, Matthias Scheffler1, Abdallah Qteish2, and •Jörg Neugebauer3 — 1Fritz-Haber-Institut der MPG, Berlin - Germany — 2Yarmouk University, Irbid - Jordan — 3MPI für Eisenforschung, Düsseldorf - Germany
Despite significant improvements in the fabrication and quality of InN, the exact values of the InN bandgap and of the band parameters are still controversially discussed. We have therefore performed quasiparticle energy calculations in the G0W0 approximation using as input the bandstructure obtained in the exact-exchange (EXX) approach. In previous studies we showed that this approach systematically provides bandgaps with an accuracy of ≈0.1 eV. Employing this approach we find a bandgap of 0.7 eV for wurtzite InN [1], suggesting an intrinsic value at the lower end of the experimentally observed range [2]. Taking the Burnstein-Moss effect into account, the increase of the apparent gap with increasing electron concentration is in good agreement with the experimentally observed blue shift of the optical absorption edge. Moreover, the concentration dependence of the effective mass, which results from the non-parabolicity of the conduction band, agrees well with recent experimental findings. The upper range of experimentally observed bandgaps is explained in terms of a defect/impurity model based on the charge neutrality level.
[1] P. Rinke et al., Appl. Phys. Lett. 89, 161919 (2006)
[2] W. Walukiewicz et al., J. Crystal Growth 269, 119 (2004)