Scanning tunneling microscopy on Ga/Si(100)

Abstract

The Ga/Si(100) surface is investigated using scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and low-energy electron diffraction. Two distinct peaks are observed on the 2\ifmmode\times\else\texttimes\fi{}2 Ga phase using STS, which are associated with one Ga unoccupied state and two Ga-Si occupied states, respectively. The latter peak is assigned to surface state bands observed using angle-resolved photoelectron spectroscopy [Surf. Sci. 242, 277 (1991)]. Regular arrays of Ga clusters are observed in STM images for the 8\ifmmode\times\else\texttimes\fi{}1-Ga phase. The spacing between Ga cluster arrays is constant, whereas the spacing between the clusters along an array fluctuates. Adjacent arrays are out of phase in the direction perpendicular to the arrays. Steps are severely deformed by the formation of the 8\ifmmode\times\else\texttimes\fi{}1-Ga phase. The initial stage and second-layer growths of the 8\ifmmode\times\else\texttimes\fi{}1-Ga phase are observed. Ga clusters disrupt the 2\ifmmode\times\else\texttimes\fi{}2-Ga phase. \textcopyright{} 1996 The American Physical Society.