Adsorption activity and selectivity of the surface of InP-CdS system semiconductors with respect to toxic microimpurities

Abstract

The mechanism of and rules governing the interaction of carbon oxides (CO and CO2) and ammonia with the surface of binary (InP and CdS) and quaternary ((InP)x(CdS)1 − x) InP-CdS system components were studied by piezoelectric quartz microweighing and IR and Raman spectroscopy. The results obtained, acid-base and other physicochemical adsorbent properties, and the electronic structure of adsorbate molecules led us to conclude that the adsorption of the gases at temperatures above 297 K was predominantly chemical in nature and largely occurred according to the donor-acceptor mechanism with the participation of coordination unsaturated “metallic” atoms. The adsorbabilities of the gases on the same adsorbent under equal conditions were different and increased in the series a(CO2) → a(NH3) → a(CO). The acid-base, adsorption, and optical properties of adsorbents changed in parallel, which was indicative of the same origin of active adsorption centers and surface biographical states. This also allowed the adsorption activity of a surface to be predicted from its acid-base properties and the volumetric properties of the initial binary compounds and elementary components. The behaviors of (InP)x(CdS)1 − x solid solutions and binary system components (InP and CdS) had common and special features. Surface characteristic-composition diagrams were used to find the system component most active with respect to CO, which was the (InP)0.95(CdS)0.05 solid solution. It was used to create a high-sensitivity and selectivity sensor.