CHARACTERIZATION OF THE SEMICONDUCTOR ELECTROLYTE INTERFACE OF P-GAASGAINP2 ELECTRODES IN ACETONITRILE SOLUTIONS/

The interfacial properties at a rotated p-GaAs/GaInP2 electrode were i nvestigated in acetonitrile solutions of metallocene redox couples. Cu rrent-voltage and interfacial capacitance measurements display minimal band edge movement with changes in solution potential, indicating a w ell-passivated surface with few surface states within 1 eV above the v alence band edge. However, analysis of the shape of the current-voltag e curves and the Mott-Schottky plots obtained in the light indicates a negative potential shift in the position of the band edges upon illum ination. The extent of band edge movement depends on the concentration of the oxidized form of the redox couple in solution. Greater band ed ge movement upon illumination was observed at low concentrations, whil e less movement was observed at higher concentrations, indicating the accumulation of photogenerated electrons. Possibilities for the existe nce of the accumulated charge in states just below the conduction band are discussed.