Photoluminescent Properties of n-GaAs Electrodes: Applications of the Dead-Layer Model to Photoelectrochemical Cells

Single-crystal samples of n-type GaAs have been used as electrodes in photoelectrochemical cells (PECs) employing aqueous ditelluride electrolyte. Photoluminescence (PL) from the electrodes can be quenched by the electric field present in the semiconductor during PEC operation. The extent of PL quenching, studied as a function of carrier concentration, excitation wavelength, and applied potential, is consistent with the dead-layer model previously used to describe PL quenching in semiconductor/metal, Schottky-barrier systems. PL quenching curves calculated by assuming that the dead-layer thickness varies with applied potential in the same manner as the depletion width differ from the experimental data, particularly in the region near the flat-band potential. Sources of these discrepancies are discussed, including the possibility that relative PL intensity reflects the manner in which applied potential is partitioned across the semiconductor-electrolyte interface. (Author)