The Effect of Al Doping on Structure and Optical Properties of ZnO Thin Films

Aluminum doped zinc oxide thin films were synthesized by the chemical vapor deposition (CVD) on the glass substrate. The optical and structural properties of these films as a function of Al content (0,1,5,10 wt.%) were investigated. The average transmittance of all films is higher than 80% at a wide wavelength of 300-800nm. The bandgap energy, calculated for all samples with different Al dopant concentration, is around 3. 35-3.56 eV. X-ray diffraction results reveal that A1/ZnO films have a hexagonal wurtzite structure with (002) preferred orientation. Top and cross-sectional scanning electron microscopy (SEM) micrographs of the prepared ZnO samples exhibit the crystalline growth structures by increasing Al concentration. Doping the ZnO with Al³⁺ influences the volume composition of ZnO:Al thin films, causes an increase in the surface roughness with an increase in the Al and O content, and a decrease in the average Zn concentration.