Quantitative investigation of the role of high-energy particles in Al2O3 thin film growth: A molecular-dynamics study

The presence of a small fraction of high-energy particles in the total particle flux is an important factor which affects the structure of atom-by-atom deposited thin films. In this paper the role of high-energy (up to 400 eV) particles is studied by molecular dynamics simulations, focused on obtaining quantitative information not accessible experimentally. Aluminum oxide is used as a test case. In the case of film-forming particles with high sticking coefficient, the results show that one to few percent of high-energy atoms is sufficient for amorphization of otherwise crystalline materials. Consequently, all film-forming atoms have to be considered separately and have the optimum energy (optimum averaged energy per atom is insufficient). In the case of energetic bombardment by other (non film-forming) particles such as Ar, the results show that the film amorphization can take place but it requires higher energies and/or much higher number of particle impacts compared to the former case. The results are important for predictions based on experimentally measured energy distribution functions, and for defining pathways for the preparation of individual crystalline phases in general.