Depletion Approximation in Semiconductor Trap Filling Analysis: Application To EL2 in GaAs

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The relative change in capacitance Delta C/C, due to trap-filling caused by a change in surface potential Delta V, is the basis of deep level transient spectroscopy (DLTS) and several related experiments. Here we formulate an exact analysis of Delta C/C, involving a numerical (N) solution of the Poisson equation, and compare with experiment and with a new analytical formula derived from a depletion-approximation (DA) solution of the Poisson equation, but without the limitations on trap density inherent in older DA formulas. Limits on the agreement of the N and DA solutions are established as a function of Delta V for the important case of EL2 in GaAs. Copyright (C) 1996 Elsevier Science Ltd