Defect analysis by transmission electron microscopy of epitaxial Al-doped ZnO films grown on (0001) ZnO and a-sapphire by RF magnetron sputtering

摘要

Microstructural investigations by cross section Transmission Electron Microscopy have been carried out on Al-doped ZnO films epitaxially grown on (0001) ZnO and a-sapphire by RF magnetron sputtering, since it is known that crystallographic defects influence the physical properties of ZnO films. Threading dislocations and basal stacking faults were the predominant defects observed in these films, which were dependent on the type of the substrate and its orientation. The orientational relationship between the ZnO:Al film and the a-sapphire was determined to be (1120)_(sapphire)||(0001)_(ZnO:Al) and [0001]_(sapphire)||[1120]_(ZnO:Al). The density of dislocations in the heteroepitaxial film of ZnO:Al on a-sapphire was higher than that of the homoepitaxial film of ZnO:Al on undoped ZnO, due to the difference in the lattice mismatch, which also affected the crystallinity of the film.