The investigation of molecular beam epitaxy growth of GaN by molecular dynamics simulation

The epitaxial growth of GaN on AlN substrate is investigated by using the molecular dynamics simulation. The effects of substrate rotating speed, the effusion source inclined angle, the substrate temperature and the flux ratio of Ga and N atoms are simulated and studied. The variation of the surface morphology and atomic scale structure are discussed in detail. It is observed that the roughness decreases rapidly as the rotating speed increases from 0 to 2 revolutions per monolayer. The crystalline quality is improved as the rotating speed increases from 0 to 5 revolutions per monolayer. The surface roughness keeps a small change as the incident angle increases from 15 degrees to 45 degrees and then increases significantly with further increase of incident angle. However, the wurtzite composition of the structure components presents a positive correlation with the incident angle. The surface morphology is much better at the N: Ga flux ratio of 0.8 than at the ratio of 1.2 and the crystalline quality at the N: Ga flux ratio of 1 is better than that at the ratio of 1.2 and 0.8 in overall trend. However, the crystalline quality at the N: Ga flux ratio of 0.8 is improved significantly and surpasses the crystalline quality at the ratio of 1 under a relatively high temperature.