Waveguide-Integrated MoTe2p- i- n Homojunction Photodetector

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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ACS Nano
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 MoTe2p-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 MoTe2 channel in p- or n-types. High-quality reconfigurable MoTe2 (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 MoTe2 absorption promises a sensitive photodetection in the telecommunication O-band from 1260 to 1340 nm, though it is close to MoTe2's absorption band-edge. A competitive photoresponsivity of 0.4 A/W is realized with a light on/off current ratio exceeding 104 and a record-high normalized photocurrent-to-dark-current ratio of 106 mW-1. The ultrasmall capacitance of p-i-n homojunction and high carrier mobility of MoTe2 promise a high dynamic response bandwidth close to 34.0 GHz. The proposed device geometry has the advantages of employing a silicon PC waveguide as the back gates to build a 2D material p-i-n homojunction directly and simultaneously to enhance light-2D material interaction. It provides a potential pathway to develop 2D material-based photodetectors, laser diodes, and electro-optic modulators on silicon photonic chips.
Funding Information: This project was primarily supported by the National Key R&D Program of China (Grant 2018YFA0307200), the National Natural Science Foundation of China (Grants 91950119, 61905196, and 62090033), Key Research and Development Program in Shaanxi Province of China (Grant 2020JZ-10), and the Fundamental Research Funds for the Central Universities (Grants 310201911cx032, 3102019JC008, and D5000210905). The authors also thank the Analytical & Testing Center of NPU for their assistance in device fabrication and characterizations. Publisher Copyright: © 2022 American Chemical Society.
lateral junction, MoTe, p- i- n homojunction, photodetector, silicon photonics, two-dimensional materials, waveguide-integrated
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Li, C, Tian, R, Chen, X, Gu, L, Luo, Z, Zhang, Q, Yi, R, Li, Z, Jiang, B, Liu, Y, Castellanos-Gomez, A, Chua, S J, Wang, X, Sun, Z, Zhao, J & Gan, X 2022, ' Waveguide-Integrated MoTe 2 p- i- n Homojunction Photodetector ', ACS Nano, vol. 16, no. 12, pp. 20946-20955 . https://doi.org/10.1021/acsnano.2c08549