Time response of Cd0.9Zn0.1Te crystals under transient and pulsed irradiation

Abstract

A CdZnTe detector based on high-quality Cd0.9Zn0.1Te 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

Millimeter-Scale Unipolar Transport in High Sensitivity Organic–Inorganic Semiconductor X-ray Detectors

“…The rise and decay times of the devices presented here (as evident in the transient X-ray photocurrent responses given in Figure d,f) proceed over several seconds. This is in contrast to commercial detector materials such as those based on the combination of cesium iodide scintillators and amorphous silicon photodiodes which have been optimized to obtain >10 frames per second, diamond single crystals (rise and fall times of ∼1.1 s and ∼0.4 s, the latter limited by measurement apparatus used), as well as cadmium zinc telluride single crystals (rise and fall times <100 ns) . As the rise and decay times are often a reflection of the charge trapping and detrapping processes taking place within the relatively disordered organic semiconductor matrix (in comparison to its inorganic counterparts), we speculate that the replacement of the current organic semiconductors or inclusion of a inorganic material possessing higher carrier mobilities are likely to lead to significant improvement in the response times.…”

“…This is in contrast to commercial detector materials such as those based on the combination of cesium iodide scintillators and amorphous silicon photodiodes which have been optimized to obtain >10 frames per second, 27 diamond single crystals 28 (rise and fall times of ∼1.1 s and ∼0.4 s, the latter limited by measurement apparatus used), as well as cadmium zinc telluride single crystals (rise and fall times <100 ns). 29 As the rise and decay times are often a reflection of the charge trapping and detrapping processes taking place within the relatively disordered organic semiconductor matrix (in comparison to its inorganic counterparts), we speculate that the replacement of the current organic semiconductors or inclusion of a inorganic material possessing higher carrier mobilities are likely to lead to significant improvement in the response times. Potential solution-processable high-mobility semiconductors include organic semiconductors developed for organic thin film transistor applications such as 6,13bis(triisopropylsilylethynyl) 30 or poly [4-(4,4- 31 The second key factor that affects the performance of the detector architecture developed for both dosimetry and imaging is the high pixel dark currents observed (Figure S4) which leads to a signal-to-noise ratio of <0.2.…”

Temporal pulsed x-ray response of CdZnTe: In detector

“…The schematic diagram of the setup used for the temporal response measurements are shown in Ref. [13] . Ultrafast x-rays were produced from a sub-nanosecond repetition rate pulsed hard x-ray generator with a changeable tube voltage from 200 kV to 350 kV.…”

Analysis of the effects of a rotating magnetic field on the growth of cadmium zinc telluride by the traveling heater method under microgravity conditions

“…Cadmium zinc telluride (CdZnTe, CZT) is an important semiconductor crystal with properties that make it suitable for radiation detection applications [1]. For example, single crystal Cd 0.9 Zn 0.1 Te is used to manufacture room-temperature X-ray and γ-ray detectors [2], and Cd 0.96 Zn 0.04 Te is used as substrate for epitaxial growth of the infrared detection material HgCdTe [3]. In particular, there has been much recent effort toward improving the growth of large, single crystals of CZT for the fabrication of portable, low-cost, sensitive devices to detect radioactive materials.…”