The effect of sulfide passivatlon on the photoluminescence properties of InAs relative to the surface orientation has been investlgated. Chemical bonds formed in the passivation process have been studied using X-ray photoelectron spectroscopy. It was found that both As-S and In-S bonds form at the (111)A face, whereas only As-S bonds form at the (111 )B face. Improvement of photoluminescence properties was found to be associated with a decrease in the surface content of the oxides and elemental arsenic. Sulfidizing results in a reduction of the surface state density by an order of magnitude.