Improved thermal stability of antimony‐doped amorphous selenium film for X‐ray flat‐panel detectors

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Abstract
Amorphous selenium (a‐Se) film is a promising photoconductive material for X‐ray flat‐panel detectors (FPD) application. However, a‐Se tends to be crystalline Se at near room temperature. This remarkable temperature sensitivity limits its practical application. To prevent the near‐room‐temperature crystallization of a‐Se film, we fabricate antimony (Sb)‐doped a‐Se films using a vacuum evaporation technique equipped with an in situ cooling trap. We experimentally demonstrate that the Sb doping improves the thermal stability of a‐Se film while possessing a similar X‐ray photoelectric conversion efficiency as the pure a‐Se film. After air annealing at 50 °C for 90 min, the X‐ray diffraction (XRD) results of the 4.1 at.% Sb‐doped a‐Se film shows no detectable crystallization diffraction peak. Upon applying an electric field of 10 V µm−1, such Sb‐doped a‐Se film exhibits dark current density below 1 nA cm−2, while under an X‐ray dosage of about 4 mGy, the annealed Sb‐doped a‐Se film shows a photocurrent density of more than 100 nA cm−2.

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