Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces
HL 71.26: Poster
Mittwoch, 28. März 2012, 16:00–19:00, Poster D
Atomic surface structure of Ge(100) surfaces in vapor phase epitaxy ambient — •Sebastian Brueckner1,2, Oliver Supplie1, Enrique Barrigon3, Henning Doescher1,2, Anja Dobrich1, Claas Loebbel1, Johannes Luzcak1, Peter Kleinschmidt1,4, and Thomas Hannappel1,2,4 — 1Helmholtz-Zentrum Berlin, Institut Solare Brennstoffe und Energiespeichermaterialien, D-14109 Berlin — 2TU Ilmenau, Institut für Physik, Fachgebiet Photovoltaik, D-98693 Ilmenau — 3Instituto de Energía Solar, Universidad Politécnica de Madrid, E-28040 Madrid — 4CiS Forschungsinstitut für Mikrosensorik und Photovoltaik, D-99099 Erfurt
Vicinal Ge(100) substrates represent almost perfect templates for III-V nucleation and are therefore established as substrates for III-V triple junction solar cells grown by metal-organic vapor phase epitaxy (MOVPE). An important requirement to achieve low defect densities in the III-V epilayers is a suitable Ge(100) surface preparation prior to heteroepitaxy. We applied in situ reflectance anisotropy spectroscopy (RAS) to study the Ge(100) surface during preparation. A contamination free MOVPE to ultrahigh vacuum (UHV) transfer system allowed us to correlate the spectra to results from various surface science methods. Processing of Ge(100) in MOVPE environment under hydrogen led to a surface free of oxides and carbon, covered by monohydrides. Vicinal Ge(100) exhibits a preferential (2×1) surface reconstruction domain, i.e. DB steps. Exposure to arsenic resulted in predominat (2×1) or (1×2) surface reconstruction domains which was controlled in situ by RAS dependent on temperature and source of As (AsH3 or As4).