Simulation of Photoelectric Transport in High-Resistivity CdTe for X-Ray Detectors

Photoelectric transport in high resistivity CdTe at room temperature was numerically simulated based on the self-consistent steady state solution of coupled drift-diffusion equations and the Poisson equation of the photo-excited electron-hole system. Relative influence of recombination and space charge induced distortion of electric field on the reduction of charge collection efficiency was investigated. It was shown that space charge effects play significant role, if concentration of deep levels exceeds 10¹³ cm^-3 at typical values of carriers´ capture cross-section. Possibility to reduce the screening effects decreasing a detector thickness to a minimum value guaranteeing full absorption of incident X-ray radiation was investigated.