Single Crystal CdSe X-ray Detectors with Ultra-High Sensitivity and Low Detection Limit
Shunyong Wei, Ming Yang, Hui Sun, Faming Li, Fei Xiao, Jihua Zou, Aobo Ren, Yixuan Huang, Zhihui Xiong, Liming Yuan, Hao Xu, Tixian Zeng, Jiang Wu, Zhiming M. Wang
Abstract
CdSe single crystals (SCs), with a relatively high atomic number, large X-ray absorption coefficients, and high carrier mobility, are expected to provide high-performance detection for X-ray. However, the difficulty of growing high-quality CdSe SC has severely limited its application in X-ray detection. In this work, we develop an unconstrained physical gas phase method and in situ annealing process to grow high-quality CdSe SCs under unconstrained conditions. Using this method, CdSe SCs exhibit natural exposure planes, ultrahigh resistivity of 5.43 × 1012 to 1.29 × 1013 Ω cm and high μτ product of 1.3 × 10–2 to 1.5 × 10–2 cm2 V–1. It is also observed that CdSe SC X-ray detectors exhibit a record sensitivity of 2.08 × 105 μC Gyair–1 cm–2 and a low detection limit of 85 nGyair s–1, which are both desired in medical diagnostics. Moreover, those devices with different crystal directions provide anisotropic X-ray detection performance. Our findings pave a new avenue to exploit high-performance CdSe SC X-ray detectors.