Waveguide-Integrated MoTe2 p–i–n Homojunction Photodetector

作者：Chen Li, Ruijuan Tian, Xiaoqing Chen, Linpeng Gu, Zheng‐Dong Luo, Qiao Zhang, Ruixuan Yi, Zhiwen Li, Biqiang Jiang, Yan Liu, Andrés Castellanos-Gómez, S. J. Chua, Xiaomu Wang, Zhipei Sun, Jianlin Zhao, Xuetao Gan · 发表于：ACS Nano · 年份：2022 · DOI：10.1021/acsnano.2c08549 · 被引用次数：55 · 研究领域：Photonic and Optical Devices、2D Materials and Applications、Neural Networks and Reservoir Computing

Two-dimensional (2D) materials, featuring distinctive electronic and optical properties and dangling-bond-free surfaces, are promising for developing high-performance on-chip photodetectors in photonic integrated circuits. However, most of the previously reported devices operating in the photoconductive mode suffer from a high dark current or a low responsivity. Here, we demonstrate a MoTe 2 p – i – n homojunction fabricated directly on a silicon photonic crystal (PC) waveguide, which enables on-chip photodetection with ultralow dark current, high responsivity, and fast response speed. The adopted silicon PC waveguide is electrically split into two individual back gates to selectively dope the top regions of the MoTe 2 channel in p - or n -types. High-quality reconfigurable MoTe 2 ( p – i – n, n – i – p, n – i – n, p – i – p ) homojunctions are realized successfully, presenting rectification behaviors with ideality factors approaching 1.0 and ultralow dark currents less than 90 pA. Waveguide-assisted MoTe 2 absorption promises a sensitive photodetection in the telecommunication O-band from 1260 to 1340 nm, though it is close to MoTe 2 ’s absorption band-edge. A competitive photoresponsivity of 0.4 A/W is realized with a light on/off current ratio exceeding 10 4 and a record-high normalized photocurrent-to-dark-current ratio of 10 6 mW –1 . The ultrasmall capacitance of p – i – n homojunction and high carrier mobility of MoTe 2 promise a high dynamic response bandwidth close t...