Observation of initial oxidation on Si(110)-16x2 surface by scanning tunneling microscopy

The initial oxidation of a Si(110)-16x2 clean surface, both at room temperature (RT) and elevated temperatures (635, 660degC), was investigated by scanning tunneling microscopy (STM). The effects of annealing (300degC, 15min) on an RT-oxidized surface were also investigated. On the RT-oxidized surface, a BN site, detected as a bright (B) spot in the filled-state image but as a normal (N) 16x2 adatom in the empty-state image, was observed. After annealing, DD, BD, and BB sites were found to exist in addition to the BN site. Here, DD (BD, BB) is a site that appears dark (bright, bright) in its filled-state image and appears dark (dark, bright) in its empty-state image. The relative population is DD>BD approx. = BN>BB. For oxidation at 635degC, DD, BD, and BN sites were observed. For oxidation at 660degC, only the BD site was observed. On the basis of these results, an atomistic process during the initial oxidation of the Si(110)-16x2 surface is discussed. (author)