Integrating 2D layered materials with 3D bulk materials as van der Waals heterostructures for photodetections:Current status and perspectives

In the last decade,two-dimensional layered materials(2DLMs)have been drawing extensive attentions due to their unique properties,such as absence of surface dangling bonds,thickness-dependent bandgap,high absorption coeffi-cient,large specific surface area,and so on.But the high-quality growth and transfer of wafer-scale 2DLMs films is still a great challenge for the commerciali-zation of pure 2DLMs-based photodetectors.Conversely,the material growth and device fabrication technologies of three-dimensional(3D)semiconductors photodetectors tend to be gradually matured.However,the further improvement of the photodetection performance is limited by the difficult heterogeneous inte-gration or the inferior crystal quality via heteroepitaxy.Fortunately,2D/3D van der Waals heterostructures(vdWH)combine the advantages of the two types of materials simultaneously,which may provide a new platform for developing high-performance optoelectronic devices.Here,we first discuss the unique advantages of 2D/3D vdWH for the future development of photodetection field and simply introduce the structure categories,working mechanisms,and the typical fabrication methods of 2D/3D vdWH photodetector.Then,we outline the recent progress on 2D/3D vdWH-based photodetection devices integrating 2DLMs with the traditional 3D semiconductor materials,including Si,Ge,GaAs,AlGaN,SiC,and so on.Finally,we highlight the current challenges and pros-pects of heterointegrating 2DLMs with traditional 3D semiconductors toward photodetection applications.

Van der Waals two-color infrared photodetector

With the increasing demand for multispectral information acquisition,infrared multispectral imaging technology that is inexpensive and can be miniaturized and integrated into other devices has received extensive attention.However,the widespread usage of such photodetectors is still limited by the high cost of epitaxial semiconductors and complex cryogenic cooling systems.Here,we demonstrate a noncooled two-color infrared photodetector that can provide temporal-spatial coexisting spectral blackbody detection at both near-infrared and mid-infrared wavelengths.This photodetector consists of vertically stacked back-to-back diode structures.The two-color signals can be effectively separated to achieve ultralow crosstalk of~0.05%by controlling the built-in electric field depending on the intermediate layer,which acts as an electron-collecting layer and hole-blocking barrier.The impressive performance of the two-color photodetector is verified by the specific detectivity(D^(*))of 6.4×10^(9)cm Hz^(1/2)W^(−1)at 3.5μm and room temperature,as well as the promising NIR/MWIR two-color infrared imaging and absolute temperature detection.