Browsing by Author "Wang, Xiaomu"
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- A MoSe2/WSe2 Heterojunction-Based Photodetector at Telecommunication Wavelengths
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2018-11-21) Xue, Hui; Wang, Yadong; Dai, Yunyun; Kim, Wonjae; Jussila, Henri; Qi, Mei; Susoma, Jannatul; Ren, Zhaoyu; Dai, Qing; Zhao, Jianlin; Halonen, Kari; Lipsanen, Harri; Wang, Xiaomu; Gan, Xuetao; Sun, Zhipeivan der Waals (vdW) heterojunctions enable arbitrary combinations of different layered semiconductors with unique band structures, offering distinctive band engineering for photonic and optoelectronic devices with new functionalities and superior performance. Here, an interlayer photoresponse of a few-layer MoSe2/WSe2 vdW heterojunction is reported. With proper electrical gating and bias, the heterojunction exhibits high-sensitivity photodetection with the operation wavelength extended up to the telecommunication band (i.e. 1550 nm). The photoresponsivity and normalized photocurrent-to-dark current ratio reach up to 127 mA W−1 and 1.9 × 104 mW−1, respectively. The results not only provide a promising solution to realize high-performance vdW telecommunication band photodetectors, but also pave the way for using sub-bandgap engineering of two-dimensional layered materials for photonic and optoelectronic applications. - Single-nanowire spectrometers
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-09-06) Yang, Zongyin; Albrow-Owen, Tom; Cui, Hanxiao; Alexander-Webber, Jack; Gu, Fuxing; Wang, Xiaomu; Wu, Tien Chun; Zhuge, Minghua; Williams, Calum; Wang, Pan; Zayats, Anatoly V.; Cai, Weiwei; Dai, Lun; Hofmann, Stephan; Overend, Mauro; Tong, Limin; Yang, Qing; Sun, Zhipei; Hasan, TawfiqueSpectrometers with ever-smaller footprints are sought after for a wide range of applications in which minimized size and weight are paramount, including emerging in situ characterization techniques. We report on an ultracompact microspectrometer design based on a single compositionally engineered nanowire. This platform is independent of the complex optical components or cavities that tend to constrain further miniaturization of current systems. We show that incident spectra can be computationally reconstructed from the different spectral response functions and measured photocurrents along the length of the nanowire. Our devices are capable of accurate, visible-range monochromatic and broadband light reconstruction, as well as spectral imaging from centimeter-scale focal planes down to lensless, single-cell-scale in situ mapping. - Waveguide-Integrated MoTe2p- i- n Homojunction Photodetector
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-12-27) Li, Chen; Tian, Ruijuan; Chen, Xiaoqing; Gu, Linpeng; Luo, Zhengdong; Zhang, Qiao; Yi, Ruixuan; Li, Zhiwen; Jiang, Biqiang; Liu, Yan; Castellanos-Gomez, Andres; Chua, Soo Jin; Wang, Xiaomu; Sun, Zhipei; Zhao, Jianlin; Gan, XuetaoTwo-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.