Sapphire orientation dependence of the microstructure of ZnO thin film during annealing

The sapphire orientation dependence of the microstructure of ZnO thin films has been studied in real-time synchrotron X-ray scattering experiments. The ZnO films with a 2400-Å-thick were grown on sapphire (001) and sapphire (110) substrates at room temperature by radio frequency magnetron sputtering. The as-deposited ZnO film on sapphire (001) has the only (002) crystal grains, while that on sapphire (110) has not only (002) crystal grains but (100) and (101) additional grains. The ZnO films were changed into fully epitaxial ZnO (002) grains both on sapphire (001) and sapphire (110) substrates with increasing the annealing temperature to 600°C. The epitaxial relationships of the ZnO grains were summarized as ZnO (00l)[100]//sapphire (00l)[110] and ZnO (00l)[110]//sapphire (110)[001].