Investigation of deep levels in high-resistivity bulk materials by photo-induced current transient spectroscopy. II. Evaluation of various signal processing methods

Abstract

For pt.I see ibid., vol.19, p.57 (1986). The aim of the paper is to describe the principles and the features of several signal processing methods suitable for exponential photocurrent decays and to evaluate each of them for the determination of the temperature dependence of the associated relaxation time and the involved trap parameters under various conditions depending both on the physical model and on the experimental procedure. Double-gate treatments lead to reliable results only in well defined circumstances. The proposed so-called four-gate technique, on the contrary, has a much more extended field of application; thus particular importance is attached to this method. The conditions of use, among others the appropriate choice of the four delay times on the transient, and some specific features have been determined by computer simulation. Computer simulation has also been used in order to evaluate the potential performances of the method in the case of several multi-level configurations. The main conclusion is that it offers increased spectral resolution in comparison with the double-gate processing.