Silicon Compatible Two-dimensional-three-dimensional Heterojunction Photodetectors

With the advent of two-dimensional materials,it has been found that two-dimensional materials in the fields of electricity,optics,and mechanics possess many excellent characteristics that are not possessed by their bulk materials.Different from the covalently bonded conventional junctions,2D-3D van der Waals heterostructures?vdWHs?allow the combination of the novel functions of two-dimensional layered materials?2DLMs?with the proven merits of well-developed bulk materials and conventional micro-electronic technologies.The silicon compatible2D-3D vdWHs offer a perspective on future application of 2DLM-based vdWHs in integrated optoelectronics.This article aims to investigate the controllable in suit fabrication of silicon compatible 2D-3D heterojunction for high-performance photodetectors with broadband response.The main research content is as follows:?1?In order to avoid complex fabrication process and interfacial contaminate from the 2D materials transfer,a few-layer?FL?-MoTe₂/Si n-n 2D-3D hererojunction photodetector?PD?with common commercial size has been fabricated,which takes advantages of few-layered MoTe₂ in-situ growing on plane silicon directly by pulsed laser deposition?PLD?method.A broadband and high-speed FL-MoTe₂/Si heterojuntion PD has been successfully fabricated via an optimized fabrication process.The resultant photodetector shows a wide response range of 300-1550 nm,with a responsivity over 0.19 AW^-1 and a detectivity of⁶.8×10¹33 Jones at zero bias.Significantly,the device yields a 3-dB bandwidth approaching 0.12 GHz with ultra-high response speed up to 52 ns,which is far better than that of most of the 2DLMs reported thus far and is comparable to that of commercial Si photodiodes.?2?In order to expand the spectral response of the Si-based PDs,a 2D-3D Graphene/Si vdWH was constructed by using graphene as the top contact electrode due to wide wavelength absorption range from ultraviolet to microwaves.The Graphene/Si vdWH shows a remarkable response at 1550 nm based on the properties of the graphene fabricated by a chemical vapor deposition?CVD?method.The device exhibits a current ration up to 1.2×10⁴ at zero bias,a linear dynamic range of 45 dB,a bias ratio of 0 V to1.2×10⁴,and a rise and fall time of response speed of 8.034?s/6.112?s,respectively.These results suggest that the simple methodology of device fabrication as presented herein can be as pathway for integration of high-speed,high-sensitivity,low-cost photodetectors based on 2D materials heterojunction.