Comments on the conduction mechanism in Schottky diodes

The diffusion and thermionic emission theories of conduction in Schottky diodes are compared in terms of the behaviour of the quasi-Fermi levels for electrons. It is shown by an analysis of published experimental data that, for medium- and high-mobility semiconductors, the quasi-Fermi level is essentially flat throughout the depletion region under forward bias, in accordance with the thermionic emission theory. Under reverse bias the electron quasi-Fermi level is flat through most of the depletion region but rises as it approaches the metal, in agreement with the theoretical calculations of Crowell and Beguwala. The hole quasi-Fermi level remains horizontal through the depletion region at a value coincident with the Fermi level in the metal.