II. Correlations Between Thermoluminescence and Thermally Stimulated Conductivity

Abstract

Correlations between corresponding thermoluminescence (TL) and thermally stimulated conductivity (TSC) glow curves are investigated in detail for a single trap depth in the presence of thermally disconnected traps (reservoir for trapped charge carriers) and a single type of recombination centers. As a result of our calculations, we conclude that both types of glow curves have identical shapes if the concentration of thermally disconnected traps is much greater than the concentration of thermally connected traps. We find pronounced differences if this inequality is not satisfied, and conclude (a) the customary practice of analyzing TSC data with the aid of methods developed for TL is inadequate if those methods are based solely on the shape of the glow peak; (b) simultaneous measurements of TL and TSC data by themselves do not provide sufficient information on all the relevant parameters entering the kinetic equations derived from the simple basic model; and (c) from correlated TL and TSC experiments, it is possible to decide (1) whether there is a charge carrier transport associated with the thermal release of trapped charged carriers and their subsequent recombination, and (2) whether there is a large concentration of thermally disconnected traps present. The validity of the customary assumptions, that the concentration of free charge carriers is much smaller than the concentration of trapped carriers, is discussed. In addition, the Dussel-Bube theory of TSC is completed by extending it to the case of low retrapping and small concentration of thermally disconnected traps.