Time response of Cd_0.9Zn_0.1Te crystals under transient and pulsed irradiation

A CdZnTe detector based on high-quality Cd_0.9Zn_0.1Te crystals was developed and tested as a monitor in high-intensity radiation fields. The current-voltage measurements were performed using thermally evaporated Au contacts deposited on the crystals, which revealed resistivity of 10¹⁰ Ω · cm. Typical leakage current for the planar devices was ∼3 nA for a field strength of 1000 V · cm^-1. The test results show that the CdZnTe detector has a fast time response, with a rise time of approximately 2 ns, when exposed to transient and pulsed irradiation of X-rays or electron beams. The decay of current curves is observed and discussed according to charge carrier trapping effects and space-charge accumulation mechanisms. It is suggested that the current decreases quickly with strengthening of the electric field, possibly because of charge de-trapping.