III-V/Si(100) heterointerfaces studied in VPE ambient via surface dimers by in situ reflection anisotropy spectroscopy

Pseudomorphically grown GaP on Si(100) is an appropriate quasisubstrate for ultrahigh efficiency III-V/Si devices. We are able to prepare preferentially double-layer stepped Si(100) surfaces with both types of majority domains in VPE ambient with in situ control by reflection anisotropy spectroscopy (RAS). From the sign of RA spectra of the final P-rich GaP/Si(100) surface we find that the polarity of the GaP epilayer depends on the type of substrate. Following a ball-and-stick model, but here using in situ RAS data as input, our findings for both preferentially A- and B-type Si(100) 2° substrates are in favor of Si-P bonds.