Solution-Processed 3D RGO-MoS2/Pyramid Si Heterojunction for Ultrahigh Detectivity and Ultra-Broadband Photodetection
Peng Xiao, Jie Mao, Ke Ding, Wenjin Luo, Weida Hu, Xiujuan Zhang, Xiaohong Zhang,*and Jiansheng Jie*
Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China
National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, P. R. China
Molybdenum disulfde (MoS2), a typical 2D metal dichalcogenide (2DMD), has exhibited tremendous potential in optoelectronic device applications, especially in photodetection. However, due to the weak light absorption ofplanar mono-/multilayers, limited cutoff wavelength edge, and lack of high quality junctions, most reported MoS2-based photodetectors show undesirable performance. Here, a structurized 3D heterojunction of RGO-MoS2/pyramid Si is demonstrated via a simple solution-processing method. Owingto the improved light absorption by the pyramid structure, the narrowedbandgap of the MoS2 by the imperfect crystallinity, and the enhanced chargeseparation/transportation by the inserted reduced graphene oxide (RGO), the assembled photodetector exhibits excellent performance in terms of alarge responsivity of 21.8 A W-1, extremely high detectivity up to 3.8×1015Jones (Jones = cm Hz1/2 W-1) and ultrabroad spectrum response ranging from 350 nm (ultraviolet) to 4.3 μm (midwave infrared). These device parametersrepresent the best results for MoS2-based self-driven photodetectors, andthe detectivity value sets a new record for the 2DMD-based photodetectorsreported thus far. Prospectively, the design of novel 3D heterojunction can beextended to other 2DMDs, opening up the opportunities for a host of high performance optoelectronic devices.