Optical Coupling of Surface Chemistry. Photoluminescent Properties of a Derivatized Gallium Arsenide Surface Undergoing Redox Chemistry

摘要

Photoluminescence (PL) can be a powerful tool for examining semiconductor-derived interfaces. In recent studies, we have demonstrate that PL from semiconductor electrodes is influenced by applied potential and the PL from semiconductors coated with Pd films is sensitive to hydrogen gas. In both the semiconductor/liquid and semiconductor/metal interfaces, PL intensity conforms to a dead-layer model that permits the mapping of the electric field in the semiconductor: electron-hole pairs formed within a distance on the order of the depletion width do not contribute to PL. These results, which indicate that bulk PL can be influenced by interfacial chemistry, have prompted us to examine PL from a semiconductor/molecular interface. We report in this paper on the PL properties of n-GaAs derivatized with a redox-active film. In particular, we demonstrate that redox chemistry in the film can alter the depletion width of the underlying semiconductor by sever hundred angstroms, as reflected in substantial changes in PL intensity satisfying a dead-layer model. Moreover, our results suggest a general strategy for designing optically coupled sensor with chemical specificity.