Investigation of deep levels in high-resistivity bulk materials by photo-induced current transient spectroscopy. I. Review and analysis of some basic problems

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Abstract
The use of photo-induced current transients as a means for the detection of deep trapping levels in high-resistivity bulk materials and for the determination of their parameters is discussed. In this perspective some experimental and theoretical problems are discussed on the basis of various models. The conditions which must be satisfied by the kinetics or experimentally in order to observe a quasi-exponential time dependence for the decay of the current corresponding to a single trap are pointed out. Special attention is devoted to various possibilities, depending on the model and on experimental conditions, for the parameters related to the trap or to other centres to be involved in exponential decays and how this can affect the evolution of the transient as a function of temperature. The conclusions of this analysis are of practical importance for the implementation of various possible multigate processing methods of computer recorded transient data, which are evaluated in Part II.