Low-dimensional van der Waals Material Based Electronics and Optoelectronics

Abstract

Low-dimensional van der Waals (vdW) materials, from two-dimensional (2D) graphene, transition metal dichalcogenides (TMDCs) to one-dimensional (1D) or quasi-1D nanowires such as niobium triselenide (NbSe3), allow dimensions down to atomic scale but still maintain the crystal structure, and exhibit exceptional great potentials for electronics and optoelectronics. My studies focus on electronic and optoelectronic characteristics of low-dimensional materials with novel device structures and explores the underlying physical mechanisms. We first achieve tungsten diselenide (WSe2) based photodetectors with high photoresponsivity and fast response by achieving ohimic contacts with 2D/2D contact structure. Furthermore, we present a few-layer black phosphene (BP) photodetector on top of a nanostructured silicon waveguide that can visualize the light-scattering patterns of the waveguide by scanning photocurrent measurement. Other the other hand, for 1D vdW materials, we demonstrate tunneling effect between crossed p-n junctions built by 1D nanoribbons. Finally, laser induced charge density wave melting is observed in suspended NbSe3 nanowires. This research work not only sheds light on the fundamental understandings on the low-dimensional materials, but also opens up new avenues for engineering future low-dimensional electronics and optoelectronics.