CHARACTERIZATION OF n-TYPE SEMICONDUCTING INDIUM PHOSPHIDE PHOTOELECTRODES.

n-type semiconducting single crystal InP (bandgap, E//B//G, equals 1. 25 eV) has been studied as a photoanode in aqueous electrolytes. Irradiation of the InP with light of energy greater than or equal to the value of E//B//G results in the flow of anodic current. In 1. 0M NaOH solutions, the onset of photocurrent is at about minus 1. 1V vs. SCE, and the current is accompanied by anodic dissolution of the electrode. The behavior of the reductants X**2** minus (X equals S, Se, Te) was investigated, and only Te**2** minus is found to be oxidized completely efficiently at the irradiated InP. For S**2** minus we could see no oxidation to elemental S, but oxidation of Se**2** minus is found to be partially competitive with photoanodic dissolution of the electrode. The band positions of InP are determined in all electrolytes by measuring the photopotential, or from differential capacitance measurements.