Research On The Controllable Growth And Performance Of WS₂/MoS₂ Heterojunction

The two-dimensional heterojunction of two-dimensional transition metal chalcogenides has an atomic-scale thickness and unique physical properties.The two-dimensional semiconductor heterojunction enriches the properties of two-dimensional materials so that two-dimensional materials with different characteristics form complementary advantages.It has enormous application potential in next-generation electronics and optoelectronics.Two-dimensional heterogeneous structures can be constructed by in-plane splicing or layer by layer stacking.However,two-dimensional heterostructures'preparation and performance research still face many challenges.The main problem is:how to obtain pure materials close to the intrinsic two-dimensional heterostructure,and how to precisely control crystals of different compositions through chemical construction The growth nucleation site,what influence does the composition of the two-dimensional heterostructure have on the properties of electrical transport,and how the charge is transferred in the in-plane heterojunction and the vertical heterojunction.In this thesis,by chemically constructing heterostructures,a one-step method for preparing vertical and lateral heterostructures by constructing a core-shell structure precursor is proposed.By taking the preparation of WS₂/MoS₂ as an example,the feasibility and reliability of this method are explored.Furthermore,the structural composition,and photoelectric properties of WS₂/MoS₂ vertical and lateral heterojunctions are studied.This paper includes the following three parts:1.The controllable preparation and growth mechanism of core-shell nanowires.The WO_x/MoO_x core-shell structure precursor was prepared by thermal evaporation and electrochemical deposition.Using a vacuum evaporation system to grow WO_xnanowires with different morphologies on a carbon cloth substrate,and compare the morphologies of samples obtained with different growth temperatures,holding time,and oxygen content through SEM tests,to obtain oxidation suitable for precursors Optimal synthesis conditions and parameters of tungsten nanowires.A certain thickness of MoO_xamorphous layer is deposited based on tungsten oxide nanowires with carbon cloth as a substrate,forming a WO_x/MoO_x core-shell structure precursor using XRD,XPS,HRTEM,and other characterization methods to explore e this structure.2.WS₂/MoS₂ vertical heterojunction controllable preparation and its growth mechanism and performance research.The WS₂/MoS₂ vertical heterojunction was successfully fabricated by a one-step method using chemical vapor deposition.The effects of different core-shell structure precursors,growth temperature,holding time,,and other growth conditions on vertical heterojunctions'preparation were studied.The optimal conditions for preparing WS₂/MoS₂ vertical heterojunction using this method are explored.A variety of characterization methods are used to illustrate that the WS₂/MoS₂ vertical heterojunction instead of an alloy is synthesized by this method,and the grown heterojunction has good crystallinity and the charge transfer process at the interface is explored.Fabricated WS₂/MoS₂ vertical heterojunction field-effect transistors demonstrate heterojunction materials'development potential in high-performance devices.3.WS₂/MoS₂ lateral heterojunction controllable device and its performance exploration.The WS₂/MoS₂ lateral heterojunction was successfully prepared by chemical vapor deposition,and a variety of characterization methods were used to illustrate the excellent crystallinity and structural composition of the lateral heterojunction.The WS₂/MoS₂ lateral heterojunction was studied by pump detection technology.The junction's ultra-fast kinetic process,explores the process of charge transfer in the lateral heterojunction.