Chemcial Vapor Deposition And Properties Of Vandium Doped Two Dimensional Tungsten Disufides Atomic Crystals

In recent years,with the discovery of graphene,two-dimensional materials have entered people's vision.Among them,two-dimensional layered transition metal chalcogenides?TMDCs?,as an important part of two-dimensional materials,have the lightest,thinnest and excellent Its excellent thermal conductivity and other excellent physical properties,represented by WS₂ and MoS₂,have broad application prospects in the fields of transistors,photodetectors,and flexible devices,and are candidates for the construction of next-generation optoelectronic devices.Although its performance is unique,single TMDCs cannot be used in multiple fields at the same time,so it is necessary to construct or dope the heterojunction of TMDCs to improve the original performance and give it more physical properties.At the same time,different fields have different requirements for the quality and size of two-dimensional materials.Therefore,it is necessary to explore and summarize the growth conditions to meet the needs of different application fields.The realization of controllable preparation of doped samples is also one of the key issues to be solved in the future.This paper focuses on low-pressure chemical vapor deposition?CVD?to grow V-doped WS₂ two-dimensional crystals,and systematically study the morphology and doping concentration of V-doped WS₂ two-dimensional crystals during different growth processes.The effect of the control has reached the purpose of controllable growth,and the electrical transport performance test has been carried out.The main research contents are as follows:?1?By chemical vapor deposition,using S powder as the sulfur source,WO₃ as the tungsten source,V₂O₅ as the vanadium source,and Si/SiO₂?300nm?as the substrate,a two-step V-doped WS₂ two-dimensional crystal was prepared by changing V-doped WS₂ two-dimensional crystals with different growth conditions can obtain a single layer of V-doped WS₂ and a nearly continuous single-layer doped thin film on a 1×1cm substrate;using a two-step method,S powder as sulfur Source,V₂O₅ powder as the V source,and Si/SiO₂?300nm?substrate with WS₂ as the substrate,obtained the V-doped WS₂ two-dimensional crystal epitaxially grown on the original WS₂;The exploration and summary were carried out to achieve the purpose of controllable preparation of V-doped WS₂ two-dimensional crystal.?2?Linear Raman,photoluminescence?PL?spectra,temperature-variant Raman and PL,transmission electron microscopy?TEM?,etc.were analyzed and characterized for the V-doped WS₂ sample,and the cleavage phenomenon of PL at room temperature was observed;Found that there is a concentration gradient in the single-layer V-doped WS₂ two-dimensional crystal,where the maximum doping concentration of V is about 9.8%;the V-doped WS₂ two-dimensional crystal is prepared as a field-effect transistor?FET?.In the test of electrical transport performance,the carrier type is p-type,which achieves the purpose of changing the performance of WS₂;the doped sample becomes smaller with the enhancement of the applied magnetic field at 2K,and the enhanced resistance with the applied magnetic field at 30K It becomes larger,there is a ferromagnetic paramagnetic transition,and the magnetic properties of WS₂ are induced by V doping.