A simple technique for determining deep-level concentrations in high-resistivity semiconductors using capacitance transients

Many of the practical difficulties of using capacitance transient techniques to determine the concentration of deep levels in the depletion region of a semiconductor diode are discussed with particular reference to high-purity germanium. A method called the /spl Delta/V/sub C//V/sub P/ technique, is shown to have many advantages for high-resistivity materials when the deep-level concentration is relatively large (N/sub T//N/sub B//spl ges/0.01) and particularly when there are temperature-dependent equivalent-circuit effects. The technique involves matching the capacitances of two different transients, both following pulses of magnitude V/sub P/ but with quiescent biases differing by /spl Delta/V/sub C/, so that the final value of the capacitance transient with reverse bias V/sub R/+/spl Delta/V/sub C/ is the same as the initial value of the transient when the reverse bias is only V/sub R/. The ratio of deep levels (causing the transient) to shallower levels is then given by /spl Delta/V/sub C//V/sub P/.<
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