Study of metal-semiconductor interface states using Schottky capacitance spectroscopy

Abstract
In a forward-biased Schottky diode, the charge of the interface states can be electrically modulated. This results in the appearance of additional capacitance whose variations with frequency, bias and temperature can be used to determine the characteristic parameters of the states (energy position, density, capture cross sections). A simple model is described, taking into account any possible charge exchanges between the interface states and the three 'reservoirs' surrounding them (conduction and valence bands of the semiconductor and conduction band of the metal). Limit cases where one or two of these exchange paths are dominant are detailed and a few typical experimental examples are given.