Nanoscale selective adsorption of disilane on the Si(111) surface partially terminated by Ga atoms

Selective adsorption of disilane, Si2H6, on the Si(111) surface partially terminated by Ga atoms has been investigated by scanning tunneling microscopy in the temperature range from 390 to 480 °C. When the substrate temperature is below 420 °C, disilane is dissociatively adsorbed in Si(111)7×7 regions, whereas it is hardly adsorbed in Si(111)∛×∛-Ga regions due to Ga termination of Si dangling bonds. The migration of precursors dissociated from disilane is not significant on the Si(111)7×7 surface below 420 °C. Consequently, precursors containing Si atoms are not supplied to Ga-terminated regions by the disilane dissociation in the Ga-terminated regions or the surface migration from 7×7 regions. Above 420 °C, precursors dissociated from disilane migrate from Si(111)7×7 regions to Ga-terminated regions, resulting in a two-dimensional island growth of Si in Ga-terminated regions.