Characterization of amorphous selenium alloy detectors for x-rays and high energy nuclear radiation detection

摘要

Synthesized amorphous selenium (a-Se) alloy materials have been characterized for room temperature high-energy nuclear radiation detector and x-ray detection applications. The alloy composition has been optimized to ensure good charge transport properties and detector performance. The synthesis of a-Se (As, Cl) alloys has been carried out by thoroughly mixing zone-refined (ZR) Se (～7N) with previously synthesized a-Se(As) and a-Se(Cl) master alloys (MS). The synthesized alloys have been characterized by x-ray diffraction (XRD), glow discharge mass spectroscopy (GDMS), differential scanning calorimetry (DSC), x-ray photoelectron spectroscopy (XPS), and current-voltage (Ⅰ-Ⅴ) characteristics measurements. Raman spectroscopy demonstrated that the a-Se(As) master alloy samples were in metastable monoclinic Se_8 states, in which seven vibrational modes are located at 40(41), 59(60), 77, 110, 133,227(228) and 251(252) cm~(-1). However, a-Se(Cl) master alloy samples are in stable form of trigonal structure of Seg ring, in which two modes at 142 and 234 cm~(-1) were found. Both Raman and energy dispersive spectroscopy (EDS) exhibited that a small amount of tellurium (Te) existed in a-Se (As, Cl) master alloy samples. DSC measurements showed that a-Se (Cl) MS and a-Se (As) MS samples have one melting point, located at ～219.6℃, whereas a-Se-As (0.52%)-Cl and Se-As(10.2%)-Cl(60 ppm) both possess two melting points, located at 221 and 220.3℃ respectively. The a-Se alloy plate detectors have been fabricated and tested and the results showed high dark resistivity (10~(-12) - 10~(-13) Ω-cm) with good charge transport properties and cost-effective large-area scalability.