Molecular dynamics simulation study of the microstructure of a-Si:H thin film grown by oblique-angle deposition

A molecular dynamics simulation has been carried out to investigate the effect of the incident angle in the oblique-angle deposition method on the atomic structure of the resulted hydrogenated amorphous silicon (a-Si:H) thin film. The atomic interaction in SiH system was calculated by Murty-Tersoff potential. The simulation results show that the a-Si:H thin film grew in a two-dimension mode at low or normal incidence (0°, 15° and 30°), however, it changed to follow a columnar or island-like mode at high incidence. As incident angles increased from 0° to 75°, the surface roughness increased, the adsorption rate decreased, and the a-Si:H thin film had more porous, lower density and higher content of the dangling bond. The analysis of atomic diffusion indicated that the incident angle played a crucial role in affecting the diffusion of atoms: the diffusion ability of high incidence was greater than that of low incidence. The growth mode, microstructure of a-Si:H thin film, and atomic diffusion ability were mainly influenced by shadowing effect.