Study On Photoelectric Properties Of Two-dimensional WSe₂

Transition metal disulfides have excellent electrical and optical properties similar to those of graphene,and their basic properties have been studied,laying the foundation for the application of these materials in many fields.WSe2 is a typical transition metal disulfide.This paper aims to explore the optoelectronic performance of WSe2,conduct experiments on the preparation,optical properties and electrical properties of WSe2 two-dimensional materials.The main work is as follows:(1)Prepared 1L,2L,3L and thin-layer WSe2 samples using mechanical stripping method to overcome the van der Waals force between WSe2 crystal layer and layer,and then confirmed the number of layers by measuring optical contrast.(2)Raman spectroscopy and photoluminescence spectra of different layers of WSe2 materials were characterized at room temperature.The multi-layer WSe2 produced a special peak around 310cm-1 because of the van der Waals force between layers,and this peak was not present in the monolayer WSe2.Prove that the thinnest sample is a single layer.And when WSe2 becomes a bulk material from a single layer,the photoluminescence peaks become weaker and red-shift occurs.(3)The study of carrier lifetime in semiconductor materials plays a crucial role in the development of high-speed nanoscale electronic devices.Ultrafast laser spectroscopy measurements were performed on single-layer WSe2,and time-resolved pump-detection techniques were used to fit differential reflected signals measured with different power pump lights.The fitted time constant was independent of the exciton density.The exciton lifetime of single layer WSe2.(4)A field effect transistor is fabricated with two-dimensional WSe2 as a channel material.The characteristics of its electrical transport are studied by testing the transfer characteristic curve,determining its semiconductor type,calculating its current switching ratio and carrier mobility,and analyze the reason.