Deposition time effects on optical gap, dark conductivity and X-ray photoresponse properties of thermal evaporated a-Se thin films
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We prepared the amorphous selenium (a-Se) thin films via thermal evaporated method with different deposition time, revealing that the increase of deposition time was propitious to improve the quality of a-Se thin films. In detail, the optical gap of a-Se thin films enhanced from 2.08 to 2.15 eV, and the transmittance showed the blue shift of absorption edges with prolonging deposition time. Further, the dark conductivity was analyzed systematically around three main physics issues. (i) The initial dark conductivity was high and decayed with test time. (ii) The dark conductivity showed a dependence of applied electric field. (iii) The dark conductivity decreased with extending deposition time. Moreover, a-Se thin films showed the improved X-ray photoconductivity gain from 1.5 to 3.1 times under exposure dose rate of 14.83 × 10−4 Gy/s of X-radiation, with a rapid photoresponse and a small applied electric field requirement.
The authors are grateful to the supports provided by National Natural Science Foundation of China (NSFC) (Grant Nos. 11675029, 51707015) and Foundation from Department of Science and Technology of Sichuan Province (Grant No. 2018JY0453).
JL, XZ, DY conceived the study, completed the experiments, and JL wrote the paper; QX, GP completed the literature search and helped the proformance characterizations and result analyses.
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Conflict of interest
The authors declare no conflicts of interest.
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