In situ control and atomic imaging of double layer steps on MOVPE prepared Si 100

Preparation of double layer steps is thought to be essential for heteroepitaxial growth of III V semiconductors on Si 100 , as single layer steps on Si 100 lead to the initiation of anti phase disorder in the epitaxial III V layer. We have investigated the surface structure of MOVPE prepared Si 100 surfaces using in situ reflectance anisotropy spectroscopy RAS and benchmarked the in situ signals to scanning tunneling microscopy STM images of the surfaces. In particular, we achieved double layer steps on differently misoriented samples by applying specific processing conditions. On 6 misoriented samples, the STM images revealed double layer steps where dimer rows were perpendicular to the step edges, so called DB steps. The corresponding RA spectra showed a characteristic derivative like feature at an energy of 3.4 eV at room temperature. In samples of 0.1 and 2 misorientation we also found a tendency towards double layer in disagreement with standard results in ultra high vacuum UHV . The main feature in the corresponding RA spectra was a peak at 3.4 eV, in contrast to the derivative like structure of the 6 spectru