High-Field Isothermal Currents and Thermally Stimulated Currents in Insulators Having Discrete Trapping Levels

The theory is developed for the isothermal and thermally stimulated currents (TSC) which flow in optically excited insulators that are subjected to high fields. The conditions for high-field and low-field TSC are defined. The high-field process is theoretically attractive since only first-order kinetics are required to describe the dynamics involved. In addition, the boundary conditions for TSC have been clearly defined for the first time. The isothermal current for a discrete trap is shown to be an exponential decay in time. The transcendental equations that result for the TSC are analyzed in considerable detail, with the result that corresponding approximate analytical expressions have been deduced which will considerably expedite the analyses of experimental data. A detailed discussion is given of the application of the theory to experimental data.