SURFACE-REACTIONS AT P-TYPE AND N-TYPE ZNSE IN AQUEOUS-SOLUTIONS

The surface chemistry of epitaxially grown p-type and n-type ZnSe in aqueous solutions was studied by photoelectrochemical methods. The first measurements on p-ZnSe in indifferent electrolyte solution show typical semiconductor electrode properties: dissolution of the solid in the dark at positive potentials and reduction of water to hydrogen under illumination at negative potentials. The influence of band gap mismatch between ZnSe and the GaAs substrate is clear for the n-type semiconductor. From a comparison of results obtained with p-type and n-type ZnSe electrodes at pH 7.0, it is concluded that the electrochemical reduction of hypochlorous acid occurs via the conduction band of the semiconductor. It is shown that ZnSe is etched chemically in hypochlorous acid solution and that selective etching with respect to the GaAs substrate is possible.