Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 52: Heterostructures

HL 52.5: Talk

Thursday, March 25, 2010, 11:15–11:30, H17

Derivation of AlN/GaN band offsets from GW superlattice band structures — •Chandrima Mitra, Christoph Freysoldt, and Joerg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, Dusseldorf, Germany

Band offsets at heterojunctions are key parameters for the design of modern electronic devices. In calculating these parameters the standard approach is to use density functional theory (DFT). Since DFT is known to underestimate band gaps, a constant ’scissor’ shift is added to match the experimental band gap. However, in doing so it is implicitly assumed that the valence band offsets can be accurately predicted within the framework of DFT. In this context a more reliable approach could be many body perturbation theory in the GW approximation which is known to produce band gaps in good agreement with experimental values. A straightforward approach would be to compare absolute GW corrections at the valence band position and add them on the DFT computed values. However, the reliability and transferability of absolute GW corrections is a delicate issue. In order to circumvent it, we perform a GW band structure calculation on a superlattice of two semiconductor materials. We demonstrate our approach for the AlN/GaN interface and analyse the GW corrections to the band offsets.