Structural and surface characterization of undoped ZnO and Cu doped ZnO using sol-gel spin coating method

In this work, the preparation of undoped and Cu doped ZnO thin films by sol-gel spin coating method was reported. Undoped ZnO was deposited on aluminium and silicone substrates followed by annealing at three different temperatures (350, 450 and 550 A degrees C) and optimized the annealing temperature of ZnO thin film for Cu doping on Al substrates as 550 A degrees C. The structural properties of undoped ZnO showed hexagonal crystal structure. The structural properties such as crystallite size, orientation and surface properties of annealed thin film samples at various temperatures are discussed. Undoped ZnO sol-gel for peak (002) give crystallite size within range 0.1-0.4 nm for Al and Si substrates. The observation was showed that the surface becomes smoother and grain size was increased for higher annealing temperature. For Cu doped ZnO, various concentration of Cu doping (0.03 M:Cu, 0.05 M:Cu and 0.07 M:Cu) was deposited on Al substrate which then undergone 550 A degrees C annealing temperature. The morphological properties of Cu doped ZnO were investigated using FESEM where the surface becomes smooth with increasing doping concentration while atomic force microscopy showed anomalous results for surface roughness and particle size. Optical properties from Fourier transform infrared spectrometer showed the presence of functional groups and the absorption range from the peak. It was revealed that the influence of Cu doping to ZnO where the changes can be seen from surface morphology and structural properties. In addition to that annealing treatment also played role in improving the crystallization process.