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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 Se8 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 Se8 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°C, 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°C respectively. The a-Se alloy plate
detectors have been fabricated and tested and the results showed high dark resistivity (1012 - 1013 Ω-cm) with good
charge transport properties and cost-effective large-area scalability.
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