As-modified Si(100) Surfaces for III-V-on-Si Tandem Solar Cells

In order to avoid formation of antiphase domains at the III-V/Si interface, which significantly can reduce the performance of photovoltaic devices, the Si(100) surface requires precise, double-atomic-step preparation. Here, we study the interaction of Si(100) surfaces with As, which is present in most application-relevant III-V MOCVD reactors, in dependence of the miscut magnitude. Combining optical in situ spectroscopy with ultra-high-vacuum-based surface analysis, we yield control over the dimer orientation on the Si: As surfaces. We demonstrate both (1x2) and (2x1) reconstructed surfaces, and atomically smooth Si(100): As 0.1 degrees surfaces with evenly spaced, double-atomic steps, which are highly suitable for subsequent III-V integration.