The Study Of Ultrafast Photocarrier Dynamics Of Monolayer Transition-metal Dichalcogenides Lateral Heterojunction

As the supporting technology of modern information technology,semiconductor technology has a very wide application basis.However,with the decrease of the scale of semiconductor devices and the increase of chip integration,semiconductor technology has gradually approached the limit of traditional silicon technology.People urgently need to develop semiconductor materials with better properties,breaking through the bottleneck of development from the physical basis and architecture of computing.Recent years,in-depth study of transition metal disulfides(TMDCs)materials has found that this kind of low-dimension semiconductor materials have excellent photoelectric properties.Depending on its unique direct band gap structure and two-dimensional heterostructure,it is expected to be applied in high-performance optoelectronic devices,optical computing and bionic computing in the future.Based on the photoelectric characteristics of two-dimensional TMDCs lateral heterostructures,the charge transfer and depletion characteristics of two-dimensional TMDCs in ultra-fast time scale are studied in this paper,which provides an important basis for the future application of two-dimensional semiconductor heterostructures in optical calculation.The innovation of the article can be summarized as follows:1.Self-built microscopy transient absorption optical testing system with Spatiotemporal resolution and self-designed control software.The system integrates time resolution,spatial resolution and spectral resolution.The time resolution is attainable 350 fs,the spatial resolution is less than 1 ?m,and the spectral resolution is attainable 1 nm.It can be used to study semiconductor materials from all directions and multi-angles.Various effects of materials and carrier relaxation characteristics at ultra-fast time scales have greatly improved the ability to study carrier characteristics of semiconductor materials.2.The ultrafast kinetics of photo-excited carriers in two-dimensional TMDCs is studied in detail at room temperature and low injection rate.The fluorescence spectra and transient absorption spectra of lateral heterostructures at different positions are determined by means of spectral resolution.It is found that there is a group of alloys formed by atom exchange at the interface of lateral heterostructure.Transient absorption imaging shows that the width of the depletion zone at the junction is about 200 nm due to the different doping types of materials on both sides.This naturally formed heterostructure with excellent photoelectric response is very suitable for future optical computing.3.The diffusion and charge exchange processes of photogenerated carriers in real space and the effects of depletion region and energy band on the carrier dynamics are dynamically characterized by space imaging.Comparing with the current research onlateral heterostructures of two-dimensional TMDCs,this paper firstly proves the existence of depletion zone and charge transfer behavior at the interface by imaging method,which provides experimental basis for the future application of this kind of heterojunctions.4.The dynamic process and transport mechanism of photo-excited carriers at the interface of TMDCs lateral heterostructures are analyzed.The key parameters of charge transfer process are extracted according to the carrier relaxation model,which lays the experimental foundation for further study of this material.