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

Abstract

The diffusion potential V_BO 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 V_BO 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 N_D, calculated in the usual way from slopes of the 1/C² plots, seem to agree within experimental error with N_D 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.