A generalized mathematical description of thermally stimulated luminescence (TL) and thermally stimulated conductivity (TSC) is presented in terms of a formulation that replaces the quasiequilibrium (QE) and kinetic-order approximations by two new functions Q(T) and P(T), respectively. These functions are related and can be described in terms of the physically meaningful processes of charge trapping, release, and recombination. With the Q(T) and P(T) functions and their relations to the reaction rates, we show that slow-retrapping (first-order) processes will be dominant in systems for which QE is satisfied, and that QE and non-first-order kinetics are incompatible. We develop general expressions for TL and TSC in terms of the Q(T) and P(T) functions and arrive at analytical solutions to the rate equations for the first-order case without the QE approximation and without the presence of Q(T) in the final equations. These general first-order equations are then parametrized and compared to curve shapes generated both from the Randall-Wilkins expressions and from numerical solutions to the rate equations. We show that the general first-order equations reproduce the numerical solutions over a wider range of parameter cases than do the Randall-Wilkins equations. In addition, we suggest a simple method for the extraction of activation energies from experimental TL and TSC peaks, independent of the QE approximation.

• Received 24 September 1993

DOI:https://doi.org/10.1103/PhysRevB.49.8029