Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 20: Inorganic/Organic Interfaces: Growth III

O 20.2: Talk

Tuesday, March 17, 2015, 10:45–11:00, MA 005

In-situ reflection anisotropy spectroscopy study of the MOCVD prepared Si(111) surface — •Agnieszka Paszuk, Weihong Zhao, Matthias Steidl, Sebastian Brückner, Oliver Supplie, Anja Dobrich, Peter Kleinschmidt, and Thomas Hannappel — Technische Universität Ilmenau, FG Photovoltaik, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau

Integrating III-V materials with Si substrates could combine the superior optoelectronic properties of the III-V compounds with the low-cost silicon technology. Further benefits may arise from applying nanowires which require less material than planar devices and might achieve efficiencies similar to today's best solar cells. By forming a p-n junction within Si substrates we could create a tandem solar cell exceeding the Shockley-Queisser limit associated with a single junction. Our approach is to grow a thin GaP buffer layer as a transition between silicon and the active III-V material. In dependence on the pre-growth Si(111) surfaces preparation, we are able to control the polarity of the GaP buffer. GaP films grown on the H-terminated Si(111) have A-type polarity, while GaP grown on Si(111) surface terminated with arsenic have B-type polarity. Here, we studied the preparation of the clean Si(111) or arsenic terminated surfaces in hydrogen ambient. By XPS we confirm complete oxide removal after high temperature annealing. Moreover, we can observe a change in the reflectance anisotropy (RA) spectrum after the deoxidation process, which depends on the Si surface termination and Si offcut direction. FTIR confirms Si surface termination by monohydride or arsenic.