Polycrystalline CdZnTe Thick Films for Low Energy X-ray: System Evaluation

Abstract

The X-ray response of polycrystalline-CdZnTe was measured by signal-to-noise (S/N) analysis. The CdZnTe material has optimal properties in a solid-state X-ray detector, and much research has focused on single crystal CdZnTe with a small-sized, silicon readout device. However, it would be difficult to apply CdTe or CdZnTe single crystal to large area, flat panel detectors, such as those used for radiography and mammography. As an alternative of single crystal CdZnTe, we have grown thick, polycrystalline CdZnTe films of high resistivity (>5times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> Ohm cm) using the thermal evaporation method on carbon substrate. A high signal-to-noise value has a direct impact on the performance of CdZnTe X-ray detectors. Important image parameters, such as dynamic range and detective quantum efficiency, rely on the signal and noise characteristics of the system. In this paper, we analyzed the properties of the X-ray detector and obtained images of the X-ray detector using the data acquisition system. The X-ray detector used the Cd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> ZnxTe (x=0.04), which used carbon substrate and gold as the electrode. The detector design is planar and 32 mmtimes10 mm in size, and it has a 1.75mmtimes1mm pixel electrode size and a detector thickness of 150 mum