Boosting responsivity and speed in 2D material based vertical p-i-n photodiodes with excellent self-powered ability
Maoxin Tian, Yufan Wang, Tianjiao Zhang, Cheng Zhang, Jialei Miao, Zheng Bian, Xiangwei Su, Zongwen Li, Jian Chai, Anran Wang, Fengqiu Wang, Bin Yu, Yang Xu, Yang Chai, Xiao Wang, Yuda Zhao
Abstract
Vertical p-i-n junctions are key components for optoelectronics to achieve fast response speed. However, a critical bottleneck lies in the complex fabrication techniques and the performance tradeoff between high responsivity and fast speed, especially under self-powered mode. Here, we illustrate the superiority of 2D materials-based vertical p-i-n photodiodes with maximized optical absorption in intrinsic layer (high responsivity), the efficient photocarrier separation (self-power ability), and the high-field drift velocity (fast speed). By optimizing the photocarrier generation/transfer dynamics via doping and thickness engineering, our device with zero voltage bias achieves high built-in electric field, leading to a high responsivity of 0.388 A W−1 and an EQE of 90.5% at 532 nm, a short intrinsic response time of sub-10 ps, a fast switching response time of 23 ns, and a high power conversion efficiency of 6.5%. Our work lays the foundation to resolve the responsivity-speed dilemma without the constraint of lattice mismatch. The development of vertical p-i-n junctions has been hindered by complex fabrication techniques and performance trade-off between responsivity and speed. Here, authors employ WSe2 thin layers to construct photodiode, reporting responsivity of 0.388 A/W and response time down to sub-10 picoseconds.