Photo-electrochemical characterisation of n-ZnSe epitaxial layers grown on n-GaAs substrates

Abstract
Photocurrent versus electrode potential (iph versus E) dependences in aqueous electrolyte have been employed to yield values for the carrier concentration, Nd, the minority carrier diffusion length Lp and the flat-band potential, Efb, for n-type electrodes comprising ZnSe epitaxially grown on n-GaAs. Samples grown by hydrogen transport from elemental sources (Zn and Se) at c.750 degrees C are shown to be n-type (Nd approximately 1*1018 cm-3) in agreement with photoluminescence measurements. Epitaxial layers of ZnSe grown on n-GaAs by organo-metallic chemical vapour deposition (OMCVD) and deliberately doped (n-type), yield carrier concentrations which are similar to values obtained for the same material grown on semi-insulating and p-type GaAs substrates. A correlation is obtained between Nd and Lp which is in agreement with the data of Lemasson and co-workers (1982) for bulk ZnSe samples.