Synthesis of 2D Layered BiI3 Nanoplates, BiI3/WSe2van der Waals Heterostructures and Their Electronic, Optoelectronic Properties

Two-dimensional layered materials (2DLMs) have attracted considerable recent interest as a new material platform for fundamental materials science and potential new technologies. Here we report the growth of layered metal halide materials and their optoelectronic properties. BiI3 nanoplates can be readily grown on SiO2/Si substrates with a hexagonal geometry, with a thickness in the range of 10-120 nm and a lateral dimension of 3-10 mu m. Transmission electron microscopy and electron diffraction studies demonstrate that the individual nanoplates are high quality single crystals. Micro-Raman studies show characteristic A(g) band at approximate to 115 cm(-1) with slight red-shift with decreasing thickness, and micro-photoluminescence studies show uniform emission around 690 nm with blue-shift with decreasing thickness. Electrical transport studies of individual nanoplates show n-type semiconductor characteristics with clear photoresponse. Further, the BiI3 can be readily grown on other 2DLMs (e.g., WSe2) to form van der Waals heterostructures. Electrical transport measurements of BiI3/WSe2 vertical heterojunctions demonstrate p-n diode characteristics with gate-tunable rectification behavior and distinct photovoltaic effect. The synthesis of the BiI3 nanoplates can expand the library of 2DLMs and enable a wider range of van der Waals heterostructures.