Photo-conductivity as a transmission phenomenon: Application to the study of β−Ga2O3 thin film

Abstract

The electrical conduction in semiconductors can be regarded as the flow of particles through an active medium. Starting from the conduction approach as a particle transmission problem, simple and closed expressions for transport coefficients are obtained in a bipolar model of a homogeneous semiconductor at non-steady-state conditions. These coefficients simplify the calculation of the conductivity as a time function and the evaluation of transport phenomena resulting from multiple processes. Noteworthily, they are independent of the dimensions of the sample, and thereby, suitable for the macroscopic case. The formulation described here can be used for the characterization of photoconductive samples from transport measurements and for the verification of band structure models. As an example, we apply this method to analyze the photo-response of a β-Ga2O3 thin film, obtaining estimates for electron (200 cm2/V⋅s) and hole (20 cm2/V⋅s) mobilities, recombination (2.53 × 10−24 cm2) and capture (3.91 × 10−20 cm2) cross-sections, concentrations of defects (deep defects: 3.068 × 1013 1/cm3, shallow defects: 3.91 × 10−20 cm2) and the density of states of the bands.