High-Performance Diamond Phototransistor with Gate Controllable Gain and Speed
Lei Ge, Bin Li, Guo Li, Xiwei Wang, Kuan Yew Cheong, Yan Peng, Jisheng Han, Shuqiang Li, Yingxin Cui, Yu Zhong, Peng Cui, Dufu Wang, Mingsheng Xu, Xiangang Xu
Abstract
This paper presents a fabricated solar-blind phototransistor based on hydrogen-terminated diamond. The phototransistor shows a large photocurrent and enhancement of responsivity over conventional two-terminal diamond-based photodetector. These enhancement effects are owing to the internal gain of the phototransistor. The fabricated phototransistor exhibits a high photoresponsivity ( R ) of 2.16 × 10 4 A/W and a detectivity ( D *) of 9.63 × 10 11 jones, with gate voltage ( V G ) and drain voltage of approximately −1.5 V and −5 V, respectively, under 213 nm light illumination. Even at ultralow operating voltage of −0.01 V, the device records satisfactory performance with R and D * of 146.7 A/W and 6.19 × 10 10 jones, respectively. By adjusting the V G, photocurrent generation in the device can be continuously tuned from the fast photoconductive effect to the optical gating effect with high optical gain. When V G increases from 1.4 to 2.4 V, the decay time decreases from 1512.0 to 25.5 ms. Therefore, responsivity, dark current, I photo / I dark, and decay time of the device can be well tuned by V G .