Study On Synthesis Of Two-dimensional MoTe₂ By Chemical Vapor Deposition

MoTe2 has received extensive attention due to its transition from bulk to monolayer,which changes from indirect band gap to direct band gap and has similar bandgap as silicon.However,due to the large van der Waals force between the atomic layers of MoTe2 bulk material,it is difficult to prepare a single layer and large-area monolayer of MoTe2 film by mechanical stripping.So how to achieve controllable large-area,high-crystalline-mass monolayer or thin two-dimensional MoTe2 thin film by chemical vapor deposition method has become a very important research topic.This dissertation is based on the controllable preparation of two-dimensional MoTe2 with large area and high crystalline quality by chemical vapor deposition.The main contents of the research are as follows:1.By improving the reaction device,a two-dimensional MoTe2 thin film is prepared in a single-zone high-temperature tube furnace under normal pressure by a chemical vapor deposition method,which makes the experimental procedure simple and cost-effective.The Optical microscope,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS)and atomic force microscopy were used to characterize the film formation quality of the prepared MoTe2 thin film.It was proved that the single layer and the few layers 1T' phase MoTe2 with good crystal quality were obtained.2.By adjusting the growth temperature,the proportion of the drug,and the position of the substrate during the preparation of MoTe2 by the CVD method,the effect of different growth conditions on the film formation quality of MoTe2 was explored and the optimum growth conditions of monolayer and thin layer MoTe2 films with better area and quality by CVD method were studied.3.Single-layer MoS2 thin films were prepared by mechanical lift-off method and transferred to MoTe2 thin films prepared by chemical vapor deposition to form MoS2/MoTe2 heterojunctions.The Raman spectroscopy and photoluminescence spectroscopy were used to investigate the related optical properties of the heterojunction.