Effect of deep traps on photo-generated carrier dynamics in high-resistivity CdTe

The effect of intragap trapping levels on transport dynamics of photo-gener ated charge carriers in semi-insulating CdTe:In bulk crystals is investigat ed, by means of nanosecond time-resolved photocurrent and electro-optic mea surements. By using below-bandgap photon energies, electrons and holes dyna mics have been independently studied. Hole current contribution dominates a t lower photon energies, leading to faster recovery times, while the electr onic component dominates transport on a 100 ns time scale. The evolution of local electric field on a ms time scale is due to charge trapping into dee p states. By comparing experimental results with an ad hoc developed drift- diffusion model, intragap energy levels and trapping parameters are obtaine d. (C) 2000 Elsevier Science B.V. All rights reserved.