Abbaszadeh Shiva, Scott Christopher C, Bubon Oleksandr, Reznik Alla, Karim Karim S
Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1, Canada.
Sci Rep. 2013 Nov 28;3:3360. doi: 10.1038/srep03360.
In this article we demonstrate the performance of a direct conversion amorphous selenium (a-Se) X-ray detector using biphenyldisnhydride/1,4 phenylenediamine (BPDA/PPD) polyimide (PI) as a hole-blocking layer. The use of a PI layer with a-Se allows detector operation at high electric fields (≥10 V/μm) while maintaining low dark current, without deterioration of transient performance. The hole mobility of the PI/a-Se device is measured by the time-of-flight method at different electric fields to investigate the effect of the PI layer on detector performance. It was found that hole mobility as high as 0.75 cm(2)/Vs is achievable by increasing the electric field in the PI/a-Se device structure. Avalanche multiplication is also shown to be achievable when using PI as a blocking layer. Increasing the electric field within a-Se reduces the X-ray ionization energy, increases hole mobility, and improves the dynamic range and sensitivity of the detector.
在本文中，我们展示了一种使用联苯二酐/对苯二胺（BPDA/PPD）聚酰亚胺（PI）作为空穴阻挡层的直接转换非晶硒（a-Se）X射线探测器的性能。将PI层与a-Se一起使用可使探测器在高电场（≥10 V/μm）下运行，同时保持低暗电流，且不会使瞬态性能变差。通过飞行时间法在不同电场下测量PI/a-Se器件的空穴迁移率，以研究PI层对探测器性能的影响。结果发现，通过增加PI/a-Se器件结构中的电场，可实现高达0.75 cm²/Vs的空穴迁移率。当使用PI作为阻挡层时，还显示出可实现雪崩倍增。增加a-Se内的电场可降低X射线电离能，提高空穴迁移率，并改善探测器的动态范围和灵敏度。
