Growth of a-axis ZnO films on the defective substrate with different O/Zn ratios: A reactive force field based molecular dynamics study

Highlights: • The O/Zn effect on the non-polar a-axis film growth is studied at the atomic scale. • The optimized film quality is achieved through a series of ReaxFF based MD study. • A film growth mode (singular atom → cluster → chains → continue film) is revealed. • The transformed way of the defective substrate to the perfect stacking is revealed. - Abstract: The understanding of the growth process and formation mechanism of non-polar ZnO films in atomic-scale is crucial in adjusting and controlling the film deposition conditions. Using the advanced reactive force field based molecular dynamics method, we theoretically studied the effect of O/Zn ratios (8/10–10/8) on the quality of ZnO films. The comprehensive investigation of energy and temperature fluctuation profile, radial distribution function, the sputtering and injecting phenomenon, and layer coverage indicated that the film grown under stoichiometric conditions possesses the optimized quality. Furthermore, the auto-transformation ability of the substrate from defective to perfect stacking was presented and discussed by comparing to the perfect structure. The instant film growth configurations, atomic layer snapshots, and the interfacial morphology evolution were provided step-by-step to reveal the defect type and initial film nucleation and growth mechanism