Research On Irradiation Effects Of Graphene And Graphene Field Effect Transistors

Due to its outstanding properties such as high carrier mobility,high thermal conductivity,good flexibility,and high mechanical strength,graphene has become an important material for constructing new nano-electronic devices.It is considered as a candidate material for the next generation of integrated circuits and has been widely used in fields such as aerospace,nuclear power,medical imaging,and high-energy physics.However,these scenarios often include various irradiation factors such as high-energy photons and charged particles,which will change the material’s lattice structure or accumulate charges when interacting with graphene.This further affects the performance and functionality of graphene electronic devices.Therefore,studying the irradiation effects of graphene and its electronic devices is of great practical significance.In this thesis,graphene and its field-effect devices are studied,and the research progress of irradiation effects of charged particles,high-energy photons,and neutrons on graphene and its field-effect transistors in domestic and foreign studies is analyzed.Irradiation experiments were carried out on single layer,bilayer,BN/graphene,and their field-effect devices using Ga~+and neutron irradiation as representatives of charged particles.The irradiation effects of different doses of Ga~+and neutrons on the three channel devices were studied,and the differences and similarities of the responses of graphene field-effect transistors to Ga~+and neutron irradiation were compared.Firstly,the preparation and testing methods of graphene and its field-effect transistors are studied in this thesis.Using a combination of photolithography,evaporation,and etching,three different channel graphene field-effect transistors,namely single-layer graphene,double-layer graphene,and BN/graphene heterojunction,are prepared.The prepared devices are tested and characterized by examining the optical microscope images of the channels,Raman spectroscopy,transfer characteristics curves,and output characteristic curves,proving the feasibility of the process preparation and the electrical performance of the graphene field-effect transistors.Based on the prepared devices,this thesis studies the Ga~+ion beam generated by the double beam focusing ion beam system on the single-layer graphene,double-layer graphene,and BN/graphene heterojunction and its field-effect transistors.The electrical and optical performance changes of different channel materials and their devices at different doses were analyzed.The differences and similarities of the responses of the three channel materials to Ga~+irradiation were compared.It was found that the three channel materials showed crystal,nanocrystal,and amorphous states with increasing heavy ion doses.Meanwhile,double-layer graphene showed a stronger resistance to irradiation than single-layer graphene during the transformation from nanocrystals to amorphous state,but the damage to graphene was exacerbated by the sputtering of BN under Ga~+irradiation in the heterojunction.Furthermore,this thesis also for the first time carried out fast neutron irradiation effects research on single-layer graphene,double-layer graphene,and BN/graphene heterojunctions and their field-effect transistors.The devices of different channel materials were studied under different neutron doses.It was found that the effect of neutrons on the three channel materials mainly occurred in the substrate because the high-energy neutrons mostly entered the substrate,affecting the insulating properties of the intermediate layer and reducing the carrier mobility.There was no significant difference in the response to neutron irradiation between double-layer graphene and the heterojunction compared to single-layer graphene.The research results of this thesis complement the experimental study on the neutron radiation effects of graphene and its field-effect transistors,enrich the study of heavy ions’radiation effects on field-effect transistors of different channel materials,and provide assistance to deepen the understanding of the radiation effects of graphene materials and devices,and promote their practical applications in irradiation scenarios.