The influence of retrapping of emitted carriers and increased free-carrier lifetime on the determination of the trap-activation energy and capture cross section in Isothermal-PICTS (Photo-Induced Current Transient Spectroscopy) has been studied by computer simulation. Solutions to rate equations under the transient state after interrupting photo-excitation have been obtained by using Newton-Raphson and Runge-Kutta methods. From the Isothermal-PICTS simulation using Arrhenius-plot, it has been confirmed that the trap-activation energy is determined with accuracy even if the retrapping of the carriers can not be neglected, and that the capture cross section is determined with some small errors even if the retrapping of the carriers can not be neglected. It has been confirmed that both of the trap-activation energy and capture cross section should be obtained from the low temperature region of Arrhenius-plot. The relation between the trap-density and amplitude of Isothermal-PICTS spectrum has been studied by the simulation and it has been confirmed that the two-dimensional distribution of trap-density in a sample surface can be obtained from the two-dimensional measurement of Isothermal-PICTS signal.
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