Lithium doping effect on microstructural and electrical properties of zinc oxide thin film grown by metal-organic chemical vapor deposition

Abstract

In this study, the undoped and Li-doped ZnO thin films were grown on Si(100) substrate using metal-organic chemical vapor deposition (MOCVD). Zinc acetylacetonate hydrate and lithium acetylacetonate solution were used as ZnO thin film precursor and Li dopant source. The effect of lithium doping on microstructural was characterized using a scanning electron microscope (SEM) and X-ray diffractometer (XRD). XRD diffractogram analysis shows that undoped and Li-doped ZnO thin films have polycrystalline hexagonal wurtzite structures with preferred peak crystal orientation (103). Li doping slightly changes the lattice parameters and cell volume of ZnO thin films through the increase of crystallite size and slightly affects the surface morphology of ZnO thin films. Current-voltage (I-V) measurement and four-point probe method were used to measure the electrical properties of lithium doped ZnO thin films. The electrical conductivity of ZnO thin films increases as Li doping is given compared to undoped films. These results are also supported by the I-V curve of Li-doped ZnO thin films by having a higher slope, indicating improvement in electrical properties.