Time-resolved photocurrent and electric field measurements in high resistivity CdTe

We studied current and electric field transients in high resistivity CdTe:In crystals by means of nanosecond time-resolved photocurrent and electro-optic sampling measurements. Electron and hole dynamics have been investigated for different excitation regimes (incident photon fluence and wavelength). A numerical solution for a drift-diffusion model in presence of several defect centers is given which allows to interpret experimental results. Current decay can be described by two time constants of about 10 and 100 ns, the first one being predominant for low incident photon energy (<1 eV). By comparison with the numerical model, the fast and slow time constants are related to hole and electron trapping, respectively. Electric field decays in a millisecond time scale. This is related to charge trapped in a deep recombination center located at 0.75 eV from the conduction band. © 2000 American Institute of Physics.