Double-layer stepped Si(100) for III–V-on-silicon integration

We demonstrate the formation of anomalous atomic double-layer surface steps on 2° misoriented Si(100) in hydrogen process ambient. Employing a contamination-free sample transfer, low energy electron diffraction and atomic resolution scanning tunneling microscopy reveal dimer rows running parallel to the step edges, i.e. D_A type steps, thought to be energetically unfavorable. Based on the interaction of the Si(100) surface with the hydrogen ambient, we propose a model whereby step formation results from interplay of surface vacancy generation, diffusion, and annihilation at the step edges. Reflection anisotropy spectroscopy enables in situ observation of Si(100) surface formation and confirms our model.