SMALL-SIGNAL DEEP-LEVEL TRANSIENT SPECTROSCOPY AS A LOCAL PROBE OF POTENTIAL FLUCTUATIONS DUE TO ELECTRICALLY ACTIVE DEFECTS

We present an analysis of the small-signal DLTS mode as regards reachi ng high spatial resolution and a localization of traps from measured s pectra. The analysis shows that both points of interest are connected with the selectivity of the rate window instrumentation (correlation f unction) used. Difficulty with applying an analytical expression for t he small-signal response to the experiment is overcome with the sugges ted approximation of the response at a peak maximum. Evaluation of the error of this approximation versus the normalized width of the excite d region for particular correlation functions leads to particular univ ersal error curves. A confrontation with the theoretical error curve f or the standard, double-boxcar correlation function was performed for a bulk level in GaAs. This revealed a crucial role of electrical poten tial fluctuations in a correct treatment of the DLTS response to the s mall-pulse excitation. The error curves suggest an original method for evaluating the amplitude of the electrical potential fluctuations aro und electrically active defects.