High-performance Near-infrared Light Photovoltaic Detector Based On Multilayered PtSe₂/Ge Heterojunction

The detection technology in the infrared region has been widely used in both military and civilian fields,and has important research value.The research focus of infrared detection has always been on the development of new technologies.With the cross-integration of quantum mechanics,microelectronic solid-state devices and other disciplines,infrared photodetector have made huge breakthroughs.The commercially available near-infrared photodetectors are currently typically made up of silicon based photodetector,which can only response to infrared illumination with wavelength shorter than¹100 nm.Moreover,these photodetectors usually have very complicated device structures,and the preparation steps are complicated.This makes them expensive and limiting their applications.To address the above predicament,an effective solution is to integrate traditional narrow bandgap semiconductors?such as Ge and GaAs?with the emerging two-dimensional?2D?layered materials to assemble hybrid heterojunctions.Therefore,a multilayered PtSe₂ film was synthesized via a one-step selenization method in this study.And the multilayer PtSe₂ film was transfered onto a Ge substrate by a sacrificial layer etching method.Then a high-performance near-infrared photodetector was prepared based on the vertical mixed heterojunction.Such heterojunctions exhibit apparent photovoltaic effect under near-infrared illuminations,indicating that our devices can operate without external power.It was found that the devices are highly sensitive to 1300,1550,1650 and even 2200 nm near-infrared illuminations,which extended the detection range of Ge-based photodetectors.And its photoresponse has good reproducibility and long-term air stability.Our multilayer PtSe₂/Ge heterojunction near-infrared photodetectors attain high responsivity and specific detectivity of 602mAW^-1 and 6.3×10¹¹ Jones under 1550 nm,respectively,along with a fast response speed of 7.4/16.7?s,at zero bias.Given the excellent photoresponse performance and the simple device geometry,the present self-driven near-infrared photodetectors are very promising for application in future optoelectronic devices and systems.