Photoemission from metal dots on GaAs(110): Surface photovoltages and conductivity

Abstract

Photoemission results from isolated dots on GaAs(110) demonstrate a temperature-dependent nonequilibrium surface photovoltage (SPV), even when the dots are metallic. Flat-band conditions are observed beneath isolated metallic dots at low temperature, while measurements for fully metallized surfaces show midgap pinning. Significantly, the SPV is shorted and approximate equilibrium is established for the dots when the electrical isolation is reduced by a thin conducting layer over the surface. We conclude that the steplike Fermi-level movement into the gap that has been associated with metallization is related to surface conductance rather than to changes in fundamental metal-semiconductor interactions.