Influence Of 3D Islands On The Adatom Diffusion And The Local Pressure Of The Atoms In The Substrates

Adatom diffusions is a primary task in the thin film research field. The study on diffusion barriers of adatom and local pressure of the atoms in the substrate at atomic level will reveal the physical nature of film growth which will be of great significance in both the development of equipments of thin film and the invention of new thin film materials. In this thesis, the diffusion of Cu adatom on the three-dimension islands (3D island) with different side-face in the homoepitaxy growth .including (100), (111) % (110) and (112) .were calculated by quasi-static molecular dynamic method (MD) and embedded atom method (EAM). We analyzed the barriers of two diffusion mechanisms in the diverging positions for different layers in the 3D island. We calculated the energy distribution of adatom along the pathway, local pressure and the movement of atoms on the substrate.The major points of this work are summarized as followings:A. The adatom diffusion on the 3D island.The three-dimension Enrilich-Schwoebel (3D-ES) barriers is greater than the two-dimension Enrilich-Schwoebel (2D-ES) barriers in diffusion process on the 3D island and do not change with the layers of the 3D island; For the 3D island with the side face (100), downhill mechanism is dominant; for (111) , uphill mechanism is probable and the morphology of the pyrometric cone may appear in the film growth ; for (110) and (112), due to the different height of the energy well in the inner corner, the structure of the quantum dot and the quantum line will emerge.B. The relationship between the diffusion barriers in the inner corner and the number of nearest neighbour atoms:The hopping diffusion is primary in the inner corner. The barriers is determined by the number of the nearest neighbour atoms round the adatom at the inner corner (three ones in the substrate are not accounted) and the contribution of the nearest neighbour atom to the barriers is 0.33eV/atom.C. The influence of 3D island on the local pressure and position of the atoms in the substrate. The influence of the 3D island on the local pressure and position of the atoms is limited at the interface in the range of 3-4 atom distance; the local pressure of the atom in the substrate at the interface will change with the variety of the side face of the 3D island and the number of the layers in the island; the position of the atoms also ascend because of the same reason of the former.