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 degrees C. When the substrate temperature is below 420 degrees C, disilane is dissociatively adsorbed in Si(111)7x7 regions, whereas it is hardly adsorbed in Si(111)root 3x root 3-Ga regions due to Ga termination of Si dangling bonds. The migration of precursors dissociated from disilane is not significant on the Si(111)7x7 surface below 420 degrees 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 7x7 regions. Above 420 degrees C, precursors dissociated from disilane migrate from Si(111)7x7 regions to Ga-terminated regions, resulting in a two-dimensional island growth of Si in Ga-terminated regions. (C) 1997 American Vacuum Society.