Microstructural analysis and optical characteristics of Cu-doped ZnO thin films prepared by DC magnetron sputtering

The study of the process interactions near the surface and bulk area of functional metal oxide semiconductor materials plays an important role for nanodevice application. Especially it is necessary to investigate the morphological, optical and physical properties of the synthesized semiconductor oxides modified by different states of dopant elements because this allows making a compound system with unique characteristics and novel properties. In this work the pure and Cu-doped ZnO (CZO) thin films were deposited on a silicon oxide (SiO₂/Si) substrate by using a direct current reactive magnetron sputtering technique. Synthesized samples were annealed at 500 °C, 700 °C, and 850 °C temperatures under oxygen atmosphere to obtain a good quality crystal structure. Then microstructural and optical properties of the pure and CZO films are systematically investigated by X-ray diffraction, scanning electronic microscopy, and spectrophotometer. The results indicate that Cu-doped ZnO films show stronger preferred orientation toward the c-axis and lattice mismatch, uniform grain size after doping of Cu. The effect of thermal annealing to morphologic and physical parameters of metal oxide thin films was analyzed as functions of the Cu dopant.