Capacitance Energy Level Spectroscopy of Deep-Lying Semiconductor Impurities Using Schottky Barriers

Abstract

The capacitance‐voltage (C‐V) relationship of a Schottky barrier diode is predicted for an energy distribution of impurity levels having spatially uniform concentration in an n‐type semiconductor. The model applies for forward and reverse bias voltages at modulation frequencies near dc and at modulation frequencies at which one or more of the deep doping levels cannot respond. Effects of partial ionization of impurity species and the effect of electrons in the depletion region are considered. It is predicted that the diode [d(1/C)/dV] versus V relationship exhibits sharp minima when the barrier height minus the applied bias is equal to the energy level relative to the conduction band edge of any of the predominant deep‐lying impurities in the semiconductor. The way in which deep lying impurities consequently affect a C‐V impurity profile analysis is discussed.