Modification of Schottky barrier height on Si (111) by Ga-termination

Abstract

The method of “partisan interlayer” (PI) was recently applied to the As-, S- and Cl-terminated surfaces of silicon and was demonstrated effective in reducing the n-type Schottky barrier height (SBH) and increasing the p-type SBH. These SBH shifts were likely driven by the expected transfer of charge from silicon to the adsorbates with larger electronegativity. In the present work, SBHs for Ag, Au and In on Si(111)3×3-Ga R30° and Si(111)6.3×6.3-Ga surfaces are studied and found to be shifted by as much as 0.2eV from those on clean Si(111)7×7, but in directions opposite to those observed previously. The present results are thus in agreement with the expected Ga to Si charge transfer and illustrate the general validity of the PI technique. However, large degrees of SBH inhomogeneity are observed for diodes on Ga-terminated surfaces, likely due to insufficient stability of these surfaces to withstand metal interaction, i.e., breakage of silicon–adsorbate bonds on the interface and the simultaneous/subsequent bond formation between metal and silicon and/or adsorbate atoms, as a result of metal deposition.