AN IMPEDANCE STUDY OF ELECTROCHEMICALLY INDUCED SURFACE-STATES AT THE P-GAP/ELECTROLYTE INTERFACE

Surface states, created and annihilated electrochemically at the p-GaP/aqueous hypobromite interface and mediating interfacial charge transfer, are revealed by the occurrence of a peak in the experimental capacitance-potential curve. On the basis of a proposed scheme for the reaction steps involved, the capacitance-potential behaviour of the p-GaP electrode under the given circumstances was simulated. The calculated curve was found to be in satisfactory agreement with the experimental one. The capacitance peak height appears to be limited by the Helmholtz capacitance of the GaP electrode, for which a value of approximately 5 μF cm-2 was deduced. © 1990.