High-speed Two-dimensional MoSe₂-based Heterojucntion Photodetectors

The material preparation, electronic structure and optical characteristics based on 2D TMDs have promoted the research of photodetector. While the main challenge for 2D TMDCs-based photodetectors for photoelectric conversion is to develop a device that simultaneously possesses a large active area, fast response speed and high sensitivity and broad-spectral response. This work have realized high speed, low value near infrared ?NIR? photodetector construction by control material synthesis and device optimize based on 2D MoSe₂ semiconductor. The main work is as follows:?1? A novel MoSe₂ NSs/Si vdWH based on solution-processed MoSe₂ overlapped nanosheets which could modulated energy band edge was fabricated via a dip-coating or spin coating process. The research indicates that the photodetector exhibits excellent NIR photoresponse characteristics, the response speed could up to 30 ns and the predicted -3dB bandwidth over 32 MHz, with a detectivity of ?1.2×1012 Jones, and noise current approaching 0.1 pA·Hz-1/2 at zero bias.?2? We first realized that MoSe₂ have grown in situ directly on plane silicon for fabricating a large-scale n-n Si/MoSe₂ vH with graphene as top electrode by PLD method. This method demonstrated that MoSe₂ films with vertically standing layered structure and reduce the interface effect, allowing the device has an ultrafast response speed ?71 ns. Besides, this device has a wide spectral range from 400 to 1000 nm, with a high detectivity of 6.1×1012 Jones, and a linear dynamic range?LDR? over 132 decibels ?dB?.Through the above study, we found that the methodology of device- fabrication provided a new pathway for the construction of high-speed, large-area and low-cost photodetectors.