Regensburg 2016 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Topical session: Integrated computational materials engineering for design of new materials III

MM 11.7: Talk

Monday, March 7, 2016, 17:45–18:00, H39

Ab initio study on GaP-Si interface formation and properties — •Andreas Stegmüller and Ralf Tonner — Fachbreiech Chemie, Philipps-Universität, 35032 Marburg

In thin-film heterostructures, interfaces determine charge carrier transport and exciton trapping. Here, the GaP-Si interface was chosen as a model system to study the interface formation and associated properties eminent for constructing optoelectronic applications. Experimental findings are reported showing GaP-Si is neither flat nor abrupt but intermixed within 8 atomic layers and faceted.[1]

Abrupt and intermixed interfaces at (001), (111), (112) and (113) are discussed and absolute formation energies from DFT applying large slab- and bulk-type supercells are presented. We separately analyzed local and cell-wide (3-5 nm) features on the atomic structure (local stress vs. material strain), atomic charges (interface charge vs. bulk-like atomic polarization (NPA)), electrostatic potential (transition and convergence through an interface vs. III/V film polarization/oscillating field) and relate them to stability. However, as the materials should be considered covalent (not ionic) and dominated by local contributions, more chemically motivated arguments (e.g. electronegativity) are needed in order to see why simple, charge-based models [2,3] are only qualitatively correct.

[1] Andreas Beyer et al., submitted 2015.

[2] Walter A. Harrison et al., Phys. Rev. B, 18, 4402-4410, 1978.

[3] M. D. Pashley, Phys. Rev. B, 40, 10481-10487, 1989.