33 research outputs found
Band gap and band parameters of InN and GaN from quasiparticle energy calculations based on exact-exchange density-functional theory
We have studied the electronic structure of InN and GaN employing G0W0
calculations based on exact-exchange density-functional theory. For InN our
approach predicts a gap of 0.7 eV. Taking the Burnstein-Moss effect into
account, the increase of the apparent quasiparticle gap with increasing
electron concentration is in good agreement with the observed blue shift of the
experimental 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. Based on the quasiparticle
band structure the parameter set for a 4x4 kp Hamiltonian has been derived.Comment: 3 pages including 3 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Contributions of point defects, chemical disorder, and thermal vibrations to electronic properties of Cd1-xZnxTe alloys
We present a first-principles study based on density functional theory of thermodynamic and electronic properties of the most important intrinsic defects in the semiconductor alloy Cd1-xZnxTe with x < 0.13. The alloy is represented by a set of supercells with disorder on the Cd/Zn sublattice. Defect formation energies as well as electronic and optical transition levels are analyzed as a function of composition. We show that defect formation energies increase with Zn content with the exception of the neutral Te vacancy. This behavior is qualitatively similar to but quantitatively rather different from the effect of volumetric strain on defect properties in pure CdTe. Finally, the relative carrier scattering strengths of point defects, alloy disorder, and phonons are obtained. It is demonstrated that for realistic defect concentrations, carrier mobilities are limited by phonon scattering for temperatures above approximately 150 K