Surface preparation of Si(1 0 0) by thermal oxide removal in a chemical vapor environment

The preparation of Si(1 0 0) surfaces in chemical vapor environments suitable for subsequent epitaxial III–V integration by chemical vapor deposition (CVD) involving metal-organic precursors was investigated by surface sensitive instruments accessible through a dedicated sample transfer to ultra high vacuum (UHV). Using X-ray photoelectron spectroscopy for inspection of the chemical surface composition, we verified the ability to obtain clean Si(1 0 0) free of oxygen or other contaminants. Annealing for 30 min in a pure hydrogen atmosphere of 950 mbar pressure was found to be sufficient if the surface temperature reached at least 950 °C. We characterized the crucial annealing step comprehensively regarding reliability, dependency on essential process parameters (such as annealing time and surface temperature). Our results verified significant differences to established Si(1 0 0) UHV preparation routines and therefore indicated a major influence of the process gas in the SiO2 removal process, hence we also considered a chemically active role of the hydrogen ambient in the deoxidation reaction. A complementary assessment of the general structure and the atomic configuration of our CVD-prepared Si(1 0 0) surfaces included low energy electron diffraction and scanning tunnelling microscopy and confirmed atomically flat surfaces with two-domain (2×1)/(1×2) reconstruction typical for completely deoxidized Si(1 0 0) as well as for a monohydride termination.