OBSERVATION OF ATOMIC-STRUCTURE BY SCANNING-TUNNELING-MICROSCOPY OF VICINAL SI(100) SURFACE ANNEALED IN HYDROGEN GAS

This paper reports on the atomic structure and adsorbed species on a vicinal Si(100) surface annealed in H-2. Annealing was carried out at 1000-1200-degrees-C under the H-2 pressure of 4-7 Torr. The annealing in ultrahigh vacuum (UHV) was also carried out for comparison. Reconstruction structures of 2 x 1 and 1 x 2 were found by scanning tunneling microscopy (STM) for the surface annealed in H-2 as well as that in UHV. The most obvious difference of the H-2-annealed surface from the UHV-annealed one is a large retreat of S(A) steps resulting in promotion of a biatomic step formation. Thermal desorption spectroscopy indicated the presence of a monohydride phase on the H-2-annealed surface, which is consistent with the 2 x 1 structure observed by STM.