Preparation And Properties Of Bi₂O₂Se And Transition Metal Chalcogenides Heterojunction Devices

Transition metal chalcogenides have an attractive and broad prospect in the preparation of optoelectronic devices due to their graphene-like and adjustable band gap properties.In order to widely use transition metal chalcogenides in optoelectronic devices,it is very important to choose suitable preparation technology and application trend.To find the best preparation technology and to reduce the contact resistance between the contact electrode and the transition metal chalcogenides are the prerequisites for the study of their photoelectric properties and the realization of their production and living applications.This paper systematically introduces our preparation of Bi2O2Se field effect transistor,WSe2 field effect transistor and Bi2O2Se/WSe2 heterojunction field effect transistor by the combination of polydimethylsiloxane and mechanical stripping method.By changing the temperature of vacuum annealing during the experiment,the most suitable temperature for the contact between metal electrode and transition metal choridides was found,the height of the schottky barrier between metal and semiconductor was reduced,and the mobility and switching ratio of the field effect transistor were increased.The main work:First,the obliquely grown Bi2O2Se sample was prepared by chemical vapor deposition,and transferred to the SiO2/Si substrate by direct pressing,and then the pre-prepared metal electrode was transferred to both sides of the semiconductor Bi2O2Se by the method of probe and microscope-assisted transfer.After annealing at 200℃ under vacuum without carrier gas for 1 hour,a metal-semiconductor junction with Ohmic contact was prepared,and a Bi2O2Se field-effect transistor was prepared.Using the same transfer method,a mechanically peeled transition metal chalcogenide-WSe2 field effect transistor was prepared,and by changing the vacuum annealing temperature,the optimal annealing temperature for the contact between WSe2 and the metal Pd electrode was found.By reducing the contact resistance between the Pd metal and the semiconductor material WSe2,the switching ratio,rectification ratio,and mobility of the WSe2 field effect transistor can be improved.On the basis of the above work,we further prepared Bi2O2Se/WSe2 heterojunction field effect transistors with bipolar switching characteristics.Analyzing its electronic structure,we believe that the Bi2O2Se/WSe2 heterojunction is a type Ⅱ heterojunction,its switching state can be adjusted by the gate or source-drain voltage,and it has a switching ratio of 105 and a light response speed of 40 μS,and its spectral response range from visible light to near-infrared light,it can be seen that Bi2O2Se/WSe2 heterojunction field effect transistors have high photoelectric performance.This work has made an active exploration and contribution to the application research of low-dimensional materials in optoelectronic devices.