Dynamics study of the adsorption and diffusion in early growth stage of AlN/α-Al2Ｏ3（0001） films

Abstract

The research of temperature effect on the surface adsorption and diffusion is an important problem for the initial growth mechanism of AlN/α-Al2Ｏ3（0001） thin films. Using the ab initio molecular dynamics method based on the first principles, the adsorption process, system energy, dynamic track and the diffusion coefficient are calculated at temperatures from 300℃ to 800℃. The results indicate that the adsorption process can be divided into three stages, the physical adsorption, the chemical adsorption and the stable surface growth state. With the temperature increasing, the average diffusivity of the particles at α-Al2Ｏ3（0001） surface is enhanced in the bonding process. The diffusion coefficient of N atom is higher than that of the Al atom, especially in the physical adsorption stage. At higher temperatures （over 700℃）, the role of desorption of the N atom is markedly strengthened, so it is unfavorable to the stable absorption of AlN. The temperature between 500℃ and 700℃ is beneficial to the stable adsorption and the growth of the AlN on α-Al2Ｏ3（0001） surface.