InP(100) surface passivation with aqueous sodium sulfide solution

Passivation of n-InP(100) surface with an aqueous sodium sulfide solution was investigated by photoluminescence and x-ray photoelectron spectroscopy techniques. It was found that even a brief treatment for 1 min turns out to be enough for an essential enhancement of the photoluminescence intensity, which comes amid etching off the surface indium phosphate layer and formation of In-S and In-OH surface chemical bonds. A longer sulfide treatment results in a smaller photoluminescence enhancement due to formation of indium oxide, in addition to In-S and In-OH bonds. Both native-oxide-covered and sulfide-treated n-InP(100) surfaces have almost no band bending. The enhancement of photoluminescence intensity after sulfide treatment can be explained by modification of the surface states spectrum due to the transformation of the surface chemical bonds.