Two-dimensional Controlled Etching Of Materials And Device Fabrication Based On Plasma/Ozone Etching

The discovery of two-dimensional materials represented by graphene is one of the major scientific achievements in this century,and it is a hot spot in materials research at present,which have a broad application prospects.At present,the main methods for preparing two-dimensional materials include chemical vapor deposition,micromechanical stripping,ion intercalation,solvothermal method and redox method,etc.The size and shape of the prepared two-dimensional material are random,and it needs to be graphically trimmed to produce specific functional devices with good performance.Therefore,two-dimensional material graphicization is the key technology for its application in micro-nano electronic devices and optoelectronic devices.Plasma and ultraviolet ozone etching are the most widely used methods for two-dimensional material graphicization.At present,plasma and ultraviolet ozone etching are mostly concerned with the etching of two-dimensional materials into the desired shape,mainly concerned with the"elimination"results,lack of research on the etching process and the change of physical properties and characteristics of two-dimensional materials in the process of related layers,doping,fluorescence,etc.This paper focuses on the changes of physical properties and properties of two-dimensional materials in the process of plasma and ozone etching.The main research contents and results are as follows:（1）Graphene was etched by oxygen and argon plasma respectively.The effects of gas ion type,gas flow rate,radio frequency power and time on the layers and properties of graphene were studied.The results show that the etching rate of argon plasma is faster than that of oxygen plasma under the same conditions.The plasma etched multilayer graphene gradually goes deeper from the top layer to the bottom layer,but it is not complete etched one layer and then etched the next layer.This is because there is some randomness in etched.After the upper layer of multilayer graphene is etched randomly,the exposed part of the next layer and the unetched part of the upper layer can be etched randomly.Further studies have shown that it is not possible to obtain monolayer graphene from multilayer graphene by plasma etching,and this conclusion can be extended to other two-dimensional materials,such as WSe₂,etc.（2）Graphene and WSe₂ were etched by ultraviolet ozone respectively,and the effects of etched time on the layers and properties of graphene and WSe₂ were studied.The results show that the effect of ozone etching on the etching process and physical properties of multilayer graphene is similar to that of plasma etching.However,when the WSe₂ is etched by ozone,a self-limiting layer is formed due to oxidation.This is because the uppermost layer of multi-layer or double-layer WSe₂ is etched by ultraviolet ozone,and at the same time a self-limiting layer generated by oxidation is formed,which prevent the WSe₂ from ozone to etch the next layer.（3）The band gap and luminescence of WSe₂ diselide were regulated by ultraviolet ozone etching and oxygen plasma etching.The results showed that the PL peak of the WSe₂ layer approached from 1.57 e V to 1.62e V of the monolayer by controlling the ozone etching time.This is because the number of layers of WSe₂ has changed due to the etching effect,and some oxygen atoms replaced Se atoms in the most surface layer,resulting in a change in the band gap.