Reactivity of Lead Chalcogenide (001) Surfaces Interacting with H2S

Abstract

The interaction of the semiconductor compounds PbS, PbSe, and PbTe with H 2 S was studied using X-ray photoemission spectroscopy performed at the synchrotron radiation facility BESSY II. For all surfaces sulfidation subsequent to dissociation of H 2 S was observed. For PbS, the sulfur atoms occupy the surface anion vacancies. In the case of PbSe, either a similar interaction or an anion substitution at the surface takes place; besides, H 2 S adsorption leads to the agglomeration of additional sulfur atoms forming S n 2- . For the reaction of H 2 S with PbTe surfaces we suggest a mechanism which includes at least three steps. The first step leads to a formation of Pb-S-Te bonds, which is also supported by the results of quantum chemical calculations performed in the framework of cluster approach. The subsequent steps include further gradual oxidation of the tellurium atoms and result finally in the formation of quite stable thiotellurite species.