Effects of deep defect concentration on junction space charge capacitance measurements

Expressions for the small signal capacitance and pulse bias-induced large signal capacitance transient of an abrupt n+ -p junction in the presence of one or more deep traps of arbitrary concentrations are presented. The expressions show that a simple inverse relationship between the measured small signal capacitance and the junction's space charge depletion width is not expected. Unexpected effects on defect capture cross section and defect concentration determination, when applied to deep level transient spectroscopy simulations, are also reported. Experimental results of both temperature dependent capacitance and transient capacitance measurements performed on electron irradiated Si n+ -p junctions are presented and analyzed in the context of these expressions. Modeling of the measured signals using these expressions is shown to be in good agreement with the experiment.