Functionalization Of Graphene And Its Application At Optoelectronic Devices

Graphene is a kind of typical 2 D material,as its properties in optical,electrical and mechanical,since it was found in the lab in 2004,has always been the focus of the scientific research.With the deepening of the study,a lot of growth methods have been reported,among these CVD is the commonest one.This approach meets some problems:how to better control the growth of the graphene layer and improve the quality of graphene.In addition to the growth of the graphene,many scientists have turned their attention to the practical application of graphene.Graphene have a lot of potential applications,but at present the most promising direction in the field of photovoltaic applications,such as super capacitor,transparent electrode and the p-n junction.P-n junction is the basic unit of semiconductor devices,seeking to preparation of graphene into p-n junction may meet a difficult problem:lacking of uniform doping type(n,p)graphene with large area,smooth surface.In this article,using hydrogen and argon gas and methane as raw materials by using the method of CVD growth of single and double graphene,with the help of PMMA solution and ferric chloride solution completed the transfer of graphene into different substrates,doping Ag and Au into graphene using thermal evaporation method,and using micro Raman spectroscopy,Fourier transform infrared spectrum(FT-IR),transmission electron microscope(TEM),elliptic polarization apparatus(SE),ultraviolet-visible-near infrared spectra(UV-Vis-NIR)and atomic force microscope(AFM)and Hall effect explored characterization of graphene and metal doped atoms graphene such as the surface atoms division,optical and electrical properties.To explore the application of graphene in optoelectronic devices,we fabricated a organic and inorganic compound UV detector with the main functional layer of ZnO,device structure for the Al/made/ZnO/ITO.By employing fluorescence spectroscopy(PL)and fluorescence emission spectrum(PLE)and so on,the optical properties of the material and devices are studied.Electrical performance of the device is studied through J-V characteristic curve.In the process of preparation,we use the solution method to improve the indium tin oxide(ITO)transparent electrode properties.A new device was prepared by using graphene to replace organic polymer PFO,and its responsivity was researched.Through these experiments draws the following conclusion:(1)In this paper,through strict control of experimental parameters in the process of preparation of graphene CVD method,graphene with high cleanliness and smooth surface could be prepared,also the carbon atomic layer can be well control.(2)Transfer completed CVD Graphene usually has the characteristics of p-type conductive.Thermal evaporation method is an effective method of metal doped,the graphene surface is smooth and flat,the doped metal uniform distribution,at the same time,metal doped can broaden the scope of graphene light absorption.Therefore,thermal evaporation method is a simple and effective method of graphene doping,which can be extended to other metal doping.(3)The light absorption coefficient of ZnO and PFO heterojunction a>2 x 105 cm-1.In wavelength of 365 nm,external bias to 2 V,rate of light power density of 0.01 mW cm-2 conditions,device detectivity can reach 3 x 1010 cmHz1/2 w-1,which means the photodetector is effective at near ultraviolet band.Furthermore,we explored the change of the ultraviolet detector performance after using graphene to replace PFO.We found that devices contain graphene have near-infrared light response to a certain extent,which shows that graphene broaden the response spectral range of the detector.