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HL: Fachverband Halbleiterphysik

HL 2: Electronic Structure Theory

HL 2.1: Vortrag

Montag, 14. März 2011, 10:15–10:30, POT 51

Quasiparticle band offsets at heterojunctions from GW superlattice calculations — •Christoph Freysoldt, Chandrima Mitra, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, Düsseldorf

The alignment of electronic bands at heterointerfaces is a key parameter for the performance of a variety of electronic devices. Theoretical calculations are an important aid in disentangling the underlying mechanisms and in designing better interfaces. Yet, the predictive capability of modern electronic structure theory’s workhorse, namely density functional theory (DFT), is limited due to the band gap problem in standard functionals. Many-body perturbation theory in the GW approximation offers a systematic way to improve upon DFT, but for practical purposes, many additional approximations must be employed that affect the absolute alignment of the GW self-energy. This severely restricts the possibility to obtain quasiparticle corrections for the heterointerface band offset from separate bulk calculations. We propose an alternative route which circumvents the transferability issues of absolute GW corrections. For this, relative GW corrections are determined for a superlattice. By choosing electronic marker levels in the valence band that are spatially well localized within either AlN or GaN, and by then correcting for the intraband dispersion of self-energy effects, we extrapolate the GW corrections of the band edges. Our results for zincblende AlN/GaN and AlP/AlAs show that using absolute GW corrections from separate bulk calculations gives errors of up to 40 % compared to the full GW calculation.