Research On Performance Of Photodetector Based On ZnO_1-x/graphene Heterostructure

Zinc oxide has become a research hotspot in semiconductor optoelectronic materials,with wide direct band gap(3.3 eV)and large exciton binding energy(60 meV)at roomtemperature,and also it is abundant in reserves and easy to obtain.However,the high resistance of zinc oxide materials seriously affects the transmission of photogenerated carriers in them,which in turn degrades the detection rate and transfer efficiency of zinc oxide UV detectors.Graphene has high electron mobility(20000 cm2/Vs)and high current density(more than 108 A/cm2),but the low absorbance of graphene to light has largely restricted its applications in the field of photodetectors.The previous study in our group found that non-stoichiometric zinc oxide(ZnO1-x)has a higher absorbance for visible light.In this work,we combined ZnO1-x with graphene to build ZnO1-x/graphene heterostructure,designed photodetector based on the heterostructure,studyed the photoelectric characteristics of them,made the following research:(1)The ZnO1-x/graphene heterostructures were successfully fabricated by magnetron sputtering ZnO1-x nanofilms on p-Si wafer and wet transfer of graphene.Compared with ZnO1-x films,the absorbance of ZnO1-x/graphene heterostructures in the visible and near-infrared regions all increased,and due to the high conductivity of graphene,under irradiation of 700 nm,The ZnO1-x film produces a current of 9 ?A,while ZnO1-x/graphene can produce the photocurrent of 552.67?A.(2)ZnO1-x/graphene/ZnO1-x sandwich photodetectors were fabricated from the bottom up based on silicon wafers with a SiO2 insulation layer.In this sandwich structure,due to the Schottky barrier,the dark current is weakest,under bias voltage of-5 V,it is only 21.78 nA.The graphene layer is used as the electron transport layer,under light irradiation,it devided the photogenerated electron-hole pairs generatedin the ZnO1-x film and increased the photocurrent,the photodetector based on sandwich structure obtained larger current gain,under illuminate of 520 nm light,the ratio of on/off is 65.8.