Study On Photoelectric Properties Of NiO-based Superimposed Transparent Conductive Films

Transparent conductive films have always been the focus of research because of their excellent optical and electrical properties.As new indium-free transparent conductive thin films,dielectric/metal/dielectric?DMD?triple-layered thin films have many advantages.The transmittance and conductivity of laminated films can be controlled because of the material and thickness of each layer can be changed,so that DMD triple films have the feature of low cost and promotion.NiO is often used as photosensors,hole transport layer of solar cells as a natural P-type semiconductor.And the application of NiO in triple-layered transparent conductive films has really started in recent years.In this experiment,we used NiO as the the dielectric layer of the multilayered films which were prepared by magnetron sputtering method.A series of DMD films were prepared:NiO?t?/Al?12nm?/NiO?t?,Ni O?40nm?/Al?t?/NiO?40nm?,Ni O?t?/Ag?11nm?/NiO?t?,NiO?30nm?/Ag?t?/NiO?30nm?.The optical and electrical properties,morphology and structure of the films were examined by UV spectrophotometer,four-probe method,X-ray diffraction?XRD?and atomic force microscopy?AFM?.The results show that,when the Al or Ag metal layer is about 10nm,the multilayer films have a better electro-optical propertie.The specific result is:?1?For NiO/Al/NiO triple-layered films,the transmittance of the films first increases and then decreases with the increase of wavelength.When the thickness of the NiO layer is in the range of 20nm-45nm,the maximum transmittance of 83%is obtained for the NiO layer of40nm,and the highest average transmittance is 77.3%.The sheet resistance decreases with the increase thickness of NiO layer,while the resistivity changes with the opposite trend.With the thickness of Al layer in the range of 9nm-14nm,the transmittance decreases with the increase of Al thickness,while the sheet resistance decreases obviously,Based on the optical and electrical properties,when the Al thickness is selected to be 12nm,the performance of the laminated film is the best.The difference between the simulated and the experimental curve is considered due to the combination of refractive index selection and film interface.T.0a.ken together,when the thickness of NiO layer and Al layer is 40nm and 12nm,the laminated films get the best optical and electrical properties.The maximum transmittance is 83%,the average transmittance is 77.3%and the sheet resistance is 441?/sq,the resistivity is4.0572×10^-3?·cm,the carrier concentration is 3.206×10²¹cm^-3.?2?For the experimentally prepared NiO/Ag/NiO multilayer films,the transmittance of the films first increases and then decreases with the increase of the Ni O layer thickness from20nm to 45nm.The maximum transmittance of the laminated films is 84%,when the NiO layer is taken at 30nm.Sheet resistance has no significant change with the thickness of NiO layer.The transmittance increases first and then decreases with the Ag layer thickness in the range of 9nm-14nm,but the sheet resistance decreases with the increase of Ag layer thickness.The simulated curves are roughly the same as the experimental ones.However,the calculated figure of the long-wavelength band in the visible region is lower than the experimental figure,which is caused by the combination of the refractive index selection and the film interface.Taken together,when the NiO layer takes 30nm,Ag layer takes 11nm,the multilayer film gets the best optical and electrical properties,with the maximum transmittance of 84%,the sheet resistance of 3.8?/sq,the resistivity is 2.1×10^-5?·cm,and the carrier concentration of7.476×10²¹cm^-3.