Fabrication And Characterization Of Graphene Photoelectric Detector

Graphene was first isolated from highly oriented pyrolytic graphite via micro-mechanical cleavage in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester.It has attracted extensive attention in fields like material science and semiconductor electronic device because of its extraordinary optical and electrical properties.It possesses extremely high carrier mobility and significant wavelength-independent absorption of 2.3% from visible to terahertz frequencies.In addition,it has excellent mechanical and thermal properties.The combination of these unique properties makes it a promising candidate for the new generation of uncooled optoelectronic detection applications with ultrafast and broadband photo-electronic response.Therefore,this thesis investigated the preparation and properties of graphene field effect structure photodetector.Firstly,the monolayer graphene with good quality is obtained on the copper foil by chemical vapor deposition and then successfully transferred onto the SiO₂/Si substrate by the solution of ammonium persulfate for the fabrication of graphene photodetector.The morphology,thickness and sheet resistance of graphene film had been characterized by scanning electron microscopy,Raman spectroscopy and four point probe devices.Secondly,the key processes of graphene photodetector are studied and optimized,such as the reactive-ion etching of patterned graphene,the choosing of the photoresists,the evaporation,the peeling and the annealing of metal electrodes.Based on these optimized processes,a sample of the graphene photodetector is prepared.Further,the photoelectric properties of graphene photodetector are tested and analyzed using Keithley 4200-SCS,under the illumination of the laser with center wavelength of 635 nm.Typical V-shaped curve is obtained,and the factors that affect the electrical characteristics of graphene are analyzed,including the substrate material,the surface doping of graphene and the contact interface of the metal/graphene.Additionally,the optical properties of the graphene are also measured and studied.Furthermore,the preparation method and characterization of graphene/silicon schottky junction photodetector are studied,it mainly introduced the preparation method,working principle and performances of this photodetector.And the I-V curve even the ration of light and dark current are tested.Furthermore,the current changes of the device atlow temperature are introduced.The thesis may provide a reliable process reference for the further research of graphene photodetector,which can provide an experimental foundation for the further study of high performance and diversification optoelectronic devices.