TRANSIENT PHOTOCONDUCTIVITY AND THERMALIZATION IN AMORPHOUS-SEMICONDUCTORS

In a number of recent publications, transient photoconductivity data for amorphous semiconductors have been interpreted in terms of the thermalization of excess charge carriers with localized states which are distributed over a range of energy. The validity of this approach, and the consequences of application of such a model in the analysis of localized state distributions are examined. It is demonstrated that the thermalization process is a complex function of trapping and release time constants, and that the influence of deep traps prevents the establishment of quasi-thermal equilibrium for shallower centers. It is shown that the model will, in the general case, yield erroneous results for the energy distribution of localized states.