|approved||osi15_supplie.pdf||2015-03-27 18:39:14||Oliver Supplie|
Author: Oliver Supplie
Requested Type: Oral
Submitted: 2015-03-13 10:03:48
Co-authors: M.M. May, S. Brückner, P. Kleinschmidt, T. Hannappel
TU Ilmenau, Institute of Physics, PV Group
Pseudomorphic GaP/Si(100) quasisubstrates are promising for metamorphic III-V/Si photovoltaic tandem cells and lattice-matched GaPN-based photochemical tandem diodes for high-efficient solar watersplitting . Preparation of the GaP/Si(100) interface, however, impacts subsequent heteroepitaxy and is not understood at the atomic scale. Analyzing reflection anisotropy spectroscopy (RAS) signals of single-domain surface dimers (free of antiphase disorder) in combination with DFT calculations, we found indirect indications for a kinetically limited formation of abrupt Si-P interfaces . Here, we study the GaP nucleation itself time-resolved with in situ RAS, which reveals that a dielectric anisotropy is formed at the heterointerface during the first alternating P and Ga precursor pulses and remains during further GaP layer growth . X-ray photoelectron spectroscopy (XPS) indicates the existence of Si-P bonds . Furthermore, XPS and RAS reveal that sub-monolayer coverages of (Ga,P) residuals from previous processes can lead to an inverted sublattice orientation of the GaP epilayer, which agrees with a change to Si-Ga interfacial bonds as predicted by DFT depending on the chemical potential during nucleation.
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