The Study Of Spin And Valley Manipulation And Photoexcited Carrier Dynamics In Transition-metal Dichalcogenides

When the semiconductor transistor rapidly approaches the nanometer scale,the classical laws gradually fail.Current leakage,device heat dissipation and other issues are increasingly serious.The traditional silicon industry is going to reach the limit.The breakthrough of the Moore's Law lies in looking for excellent performance materials and precise control of electrons.Transition metal disulfides(TMDCs),which have been widely studied in recent years,have excellent optical and electrical properties and can be used in optical interconnects,optical networks,ultrafast lasers,and high performance optoelectronic devices.In this paper,based on the ultrafast nonlinear optical properties of TMDCs and the kinetics of valley polarization of carriers,an all-dimensional,multidimensional and multidisciplinary experimental study is conducted to determine whether this material can be used in photon neural networks and light computing with theoretical guidance.The main contribution and innovations of this paper are as follows: 1.A microscopy nonlinear optical measurement system was constructed and the system automatic control software was designed and programmed.Compared with the traditional artificial experiment,the system improves the optical experiment efficiency by about 90 times and the signal-to-noise ratio of the test system by about two orders of magnitude.At the same time it greatly expands the application range of nonlinear optical measurement technology.2.The ultrafast nonlinear optical properties of carriers in low-dimensional TMDCs under high temperature and large injection conditions were investigated.The effect of nonambient temperature on the ultrafast relaxation of carriers in TMDCs was also investigated to make clear temperature-independence of their bandgap,lattice structure and carrier mobility.Broadband spectra absorption and intense exciton band reconstruction were found.Compared with the current researches,this paper focuses on the carrier dynamics and band-reformation of TMDCs in a variety of extreme experimental conditions in order to explain the broad-band absorption of TMDCs and the noval inner-bandgap absorption.3.The novel physical phenomena and physical mechanisms underlying the carrier transport in low-dimensional quantum systems were studied.Compared with the traditional theoretical research,this paper is application-oriented.It experimentally verified the energy valley polarization characteristics of carriers in TMDCs.The paper designed and verified a multi-level logic gate,and proposed a robust enhancement scheme.