Structural Characteristics and Annealing Effect of ZnO Epitaxial Films Grown by Atomic Layer Deposition

Structural characteristics of the ZnO epitaxial films grown on c-plane sapphire by the atomic layer deposition method were thoroughly studied. The in-plane axes of the e-plane oriented ZnO layers are predominantly aligned with that of the sapphire substrate, yielding the relationship of {10 (1) over bar0}(ZnO) parallel to {10 (1) over bar0}(Al2O3). The minor orientation with a 30 degrees in-plane twist configuration, that is, {10 (1) over bar0}(ZnO) parallel to {11 (2) over bar0}(Al2O3),which is more commonly observed in ZnO films grown by metal organic chemical vapor deposition, pulsed laser deposition, and other methods, only amounts to less than 3% and can be eliminated by thermal annealing. The structure of the ZnO, epi-films exhibits significantly improvement upon thermal annealing, and intrinsic types of basal plane stacking faults are the predominant Structural defects in the ZnO after thermal treatment. The effect of post growth thermal treatment is reported in this work.