Systematic analysis of semiconductor photoconductivity dynamics under different laser excitations: two- and three-level models

Abstract

A numerical study of a model photoconductor under pulsed and continuous-wave laser excitation is presented. From the solution of a system of partial differential equations related to the populations of the conduction and valence bands, we analyze the time behavior of the photoexcited concentrations of electrons and holes where the diffusion phenomena and the presence of electric field are neglected. Additionally, for the three-level model, the population of trap levels is also introduced and analyzed as a third variable. The dynamics of electrons, holes and traps levels concentrations are studied in the presence of different types of pulse and harmonic laser photoexcitations. We show that an improved physical insight is obtained through a systematic analysis of the influence of the main physical parameters, such as generation and recombination rates, between the available energy levels.