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

摘要

Amorphous selenium (a-Se) film is ,a promising photoconduc-tic material for X-ray flat-panel detectors (FPD) application. However. a-Se tends to be crystalline So 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 ev aporation technique equipped with an in situ cooling trap. We experimentally demonstrate that the Sb doping improves the thermal stahility of a-Se film while possessing a similar X-ray photoelectric conversion efficiency as the pure a-Se film. After air annealing at 50℃ for 90 rnin, the X-ray diffraction (XRD) results of the 4.1 at.% Sb-doped a-Sc film shows no detectable crystallization diffraction peak. Upon applying an electric field of 10Vμm~(-1) , such Sb-doped a-Se film exhibits dark current density below 1 nA cm~(-2). while under an X-ray dosage of about 4mGy. the annealed Sb-doped a Se film shows a photocurrent density of more than l00nA cm~(-2)