Evolution behavior of C and Si atoms on diamond (001) surface: A first principle study

A novel type of diamond/Si nano-composite thin films is proposed to improve the performance and quality of nano-diamond films. The function of Si atoms in the formation was explored by analysing the evolution of C and Si atoms in diamond/Si nano-composite films. The adsorption, migration, and evolution of the C–Si island configurations on the diamond (0 0 1) surface was studied by using first-principle method based on the density functional theory (DFT). The results indicate that the maximum adsorption energy of the C and Si atoms on the diamond (0 0 1) surface are 4.96 and 4.39 eV, respectively, which implies Si atoms tend to diffuse out of the diamond crystal and formed C–Si interface on the grain boundary. In the same migration pathway, the migration activation energy of the Si particle was 0.865 eV, and the C particle was 1.957 eV. Therefore, the Si atoms migrated easily onto diamond (0 0 1) surface. In the 3C–1C-1 configuration, the C atoms outside the 3C island migrated into the island to form a 4C island in the diamond structure. However, in the 3C–1C-2 configuration, the C atoms outside the 3C island did not migrate into the 3C island, which destroyed the diamond surface. In the 3C–1Si-1 and 3C–1Si-2 configurations, Si atoms migrated into the 3C island to form the 3C1Si island. The Si atoms stabilized the structure of the diamond and eliminated non-diamond carbon atoms, hydrogen atoms and defects in the nano-diamond films.