The Photovoltaic Materials And Devices Based On ZnO Nanorods

Zinc Oxide(Zn O)is an important wide band gap compound semiconductor material with excellent photoelectric properties and rich morphological structures,which of the band width is 3.37 eV and the exciton binding energy is as large as 60 meV at room temperature.Nano-ZnO has many special properties such as surface effect,quantum size effect and macroscopic quantum tunneling effect with simple preparation process and low cost,which makes ZnO become an extremely important member of sensors.Moreover,nano-ZnO based photoelectric conversion materials and devices have been widely concerned and researched in various application fields.Graphene(G)has a lot of excellent characteristics such as good electron transport properties and light transmittance,excellent mechanical and thermal properties,high specific surface area and ultra light weight due to its unique hexagonal lattice structure;and the raw materials of graphene are with abundant reserves.These advantages make graphene attract much attention and extensively applied in many fields with the rapid development of microelectronics and integrated circuit technology today.In this paper,one dimensional Zn O nanorod-array-films(ZNF)were grown via hydrothermal process on ZnO seed crystal substrates prepared by Czochralski method and magnetron sputtering method,respectively.Graphene was prepared by oxidation-reduction(OR)method and finally metal-ZnO and Graphene-ZnO(G-Zn O)Schottky junctions were successfully obtained;and the preparation process,growth mechanism and their influence factors of ZNF,graphene and ZnO based Schottky junctions were investigated by various means of characterization.The main research contents and results are as follows:1.ZnO crystal seeds were prepared on glass substrates by the Czochralski method and magnetron sputtering method,respectively.Then the one-dimensional ZnO nanorod array films were grown on the substrates through hydrothermal method.The scanning electron microscope(SEM)and X ray diffraction(XRD)results showed that the prepared ZnO nanorods were hexagonal prisms and preferentially grown along the direction of c axis(0001),and all the ZNF were with very high purity.The crystallinity,size and arrangement uniformity and perpendicularity of the ZnO nanorods arrays grown on ZnO seed crystal substrates prepared by magnetron sputtering method were much better than that of Czochralski method.The size of ZnO nanorods was related to the concentration of hydrothermal solutions,the growth time and the morphology of seed crystal,which can be used to control the size of Zn O nanorods and the density of Zn O arrays.2.ZnO crystal seed layer was prepared by magnetron sputtering on five kinds of metal substrates including Aluminum(Al),Chrome(Cr),Nickel(Ni),Titanic(Ti),Iron(Fe),respectively.And then the ZnO nanorod arrays were successfully grown on these substrates via hydrothermal method.The photoluminescence(PL),I-V curve and XRD test results showed that pure ZnO with high crystallinity,little deep level defects and good crystal quality was obtained.And the ZnO nanorod arrays were uniform,regular and in good order.Besides,semiconductor-metal Schottky junctions were formed between ZnO nanorod arrays and metal substrates.3.Graphene thin films were prepared by oxidation-reduction method(OR).The Raman spectra showed that the graphene films had good crystallinity,fewer defects and larger thickness with high temperature reduction at 1050? compare with the reduction at 500?.The contrast experimental results showed that the reduction degree of graphene was related to the reduction temperature and the state of graphene oxide before reduction.4.ZnO nanorod arrays were combined with graphene prepared by oxidation-reduction(OR)and CVD methods respectively.And self powered photodetectors based on G-ZnO Schottky junctions with stable Schottky barriers and good performance were successfully prepared by p-type doping of graphene and n-type doping and surface treatment of ZnO.In this work,the ZnO nanorod arrays grown by the two-step method are not only controllable in size and morphology,but also highly reproducible,which plays an important role in the preparation of ZnO nanorods based optoelectronic materials and devices.