Depletion Capacitance and Diffusion Potential of Gallium Phosphide Schottky-Barrier Diodes

Abstract

The diffusion potential VBO and the intercept V0 of the 1/C2 vs bias plots for n-type GaP-metal Schottky-Barrier diodes have been measured. Photoresponse measurements indicate that VBO is not sensitive to the thickness δ of the interfacial separation between the GaP and the metal; V0 is observed to increase rapidly with δ. The 1/C2 plots are linear in all cases, with slopes independent of V0. The values for the donor density ND, calculated in the usual way from slopes of the 1/C2 plots, seem to agree within experimental error with ND calculated from the resistivity of the GaP. Several models are proposed for the metal-interfacial-layer-semiconductor system in order to explain this behavior. The GaP-metal diodes are shown to be best characterized by a model which includes a bias-dependent charge in surface states at the semiconductor surface.