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HL: Fachverband Halbleiterphysik
HL 68: Heterostructures and interfaces
HL 68.5: Talk
Wednesday, April 2, 2014, 16:00–16:15, POT 051
In situ RAS and ab initio DFT study of GaP/Si(100) interface structures — •Oliver Supplie1,2, Sebastian Brückner1,2, Oleksandr Romanyuk3, Peter Kleinschmidt1,2, Henning Döscher1,2,5, Frank Grosse4, and Thomas Hannappel1,2 — 1Helmholtz-Zentrum Berlin, Institute Solar Fuels — 2TU Ilmenau, Institut für Physik, FG Photovoltaik — 3Institute of Physics, Academy of Sciences of the Czech Republic, Prague — 4NREL, Golden, CO, USA — 5Paul-Drude Institut für Festkörperelektronik, Berlin
GaP/Si(100) is considered as quasi-substrate for lattice-matched GaPN/Si photoelectrochemical tandem diodes [1]. The formation of the crucial polar-on-nonpolar heterointerface in vapor phase epitaxy ambient is studied here by in situ reflection anisotropy spectroscopy (RAS) in combination with ab initio density functional theory (DFT). We can choose between energetically and kinetically [2] driven Si(100) step formation, which results in either A-type or B-type majority domains of Si dimers. The sublattice orientation of the subsequently grown GaP film depends on the type of Si surface. In an abrupt interface model [3], Si–P bonds are found to be favored. Ab initio DFT calculations [4] show that Si–P bonds are energetically favored over Si–Ga bonds at abrupt interfaces. Charge can be compensated in an in-plane (2x1) interface unit cell with a Si to P (Ga) atomic mixing ratio of 0.5:0.5 which is favorable in thermodynamic equilibrium.
[1] Döscher et al., ChemPhysChem 13 (2012) 2899.
[2] Brückner et al., PRB 86 (2012) 195310.
[3] Beyer et al., JAP 111 (2012) 083534.
[4] Romanyuk et al., PRB 88 (2013) 115312.