The distortion of the interface-state spectrum due to nonequilibrium occupancy of the interface states at the metal-semiconductor interface

Abstract

Using the Shockley–Read–Hall statistics and considering the charge exchanges between metal and interface states, the effects of nonequilibrium occupancy on the interface-state spectrum measured from a forward-biased Schottky barrier diode have been studied, both theoretically and experimentally. It is shown that due to the rapid interaction between the interface states and the minority-carrier reservoirs at the interface, the energy density of the interface states experimentally measured can exceed that of the actual one when the constant-temperature Schottky capacitance spectroscopy and current-voltage methods are used. Moreover, taking the applied voltage drop across the interfacial (dipole) layer into consideration, the apparent interface-state spectra in the vicinity of the thermal equilibrium Fermi level for various metal- and metal-silicide-Si Schottky barrier contacts can be well interpreted by a simplified interface state occupation function model, which is physically consistent with the nonideal current transport characteristics of the Schottky barrier diodes.