Influence And Regulate Of UV/Ozone On The Characteristics Of Graphene/MoS₂ Heterojunction

In recent years,owing to the atomic thickness and high-quality layer structure,graphene,two-dimensional transition metal chalcogenides,and other two-dimensional（2D）layered materials have attracted wide attentions.In addition to being used alone,different 2D materials can also be stacked vertically or horizontally to form van der Waals heterojunctions with various characteristics.The tunable or modification of 2D materials and van der Waals heterojunctions has also expanded their application scope,making them have broad development prospects in many fields.This article focuses on the monolayer graphene/molybdenum disulfide（graphene/MoS₂）van der Waals heterojunction,and studies the preparation methods of the graphene/MoS₂heterojunction and its field effect transistors（FET）,and regulates the properties of the heterojunction and FET under UV/Ozone treatment.The main contents are as follows:（1）The preparation parameters of graphene/MoS₂ heterojunction and FET are studied.The growth conditions such as reaction temperature,heating temperature,gas flow rate and molybdenum source composition in the preparation of monolayer MoS₂by chemical vapor deposition were researched.The preparation process of graphene/MoS₂ FET is studied,and conditions such as exposure beam current and evaporation speed are explored.（2）The effect of UV/Ozone treatment on the graphene/MoS₂ heterojunction prepared by chemical vapor deposition is studied in detail.Using Raman spectroscopy,photoluminescence spectroscopy,X-ray photoelectron spectroscopy to the structure and characteristics of the heterojunction under different processing time conditions.The effects of the existence of MoS₂ and the change of the heterojunction structure on the charge transfer at the interface of the heterojunction,the energy band structure and the height of the Schottky barrier are studied.In addition,we also study the effect of UV/Ozone treatment on the two heterojunctions prepared by mechanical exfoliated method.（3）The field effect transistor with mechanically exfoliated graphene/MoS₂ van der Waals heterojunction as the channel material is treated with UV/Ozone,and the performance changes of its output characteristics,transfer characteristics and noise characteristics before and after the treatment are tested.Then,based on the test results,the threshold voltage,rectification ratio,charge neutral point and other parameters were extracted.We studied the changes in the properties of FET before and after UV/Ozone treatment and analyzed the mechanism.