(a) The measured photocurrent and corresponding gain at 532 nm of the devices biased at 1.1 V_br, which show negligible variations compared with the values before radiation. (b) Leakage current as a function of reverse voltage before and after radiation at room temperature. During the radiation, the samples are biased at 0.9 V_br, 1.1 V_br and unbiased, respectively, with the total radiation dose of 100 krad(Si) and dose rate of 50 rad(Si)/s. The inset shows the negligible changes of V_br after radiation.