The Film Structure Of Crystal Epitaxial Growth And Dislocations Movement By Phase-Field Crystal Method

It is well known that the misfit between substrate and film, misfit dislocations, morphologies and the critical height of the film in the process of epitaxial always are focused by scientists. The features during the evolution process of epitaxial film are described by the morphologies, misfits and crystal lattice structure. Hence, understanding the processes and the mechanism by which the various defects are formed is imperative for developing methodologies to minimize the density of defects in the epilayer. It is difficult to investigate the epilayer growth process by traditional experiments due to limitation of raw materials and advanced equipment. To compute or simulate the process by Molecular Dynamics method, Monte Carlo model can obtain well results on atomic scale, phase-field model could show the continuous and more length scale morphologies. But the simulating method above-mentioned cannot reflect the microscopic lattice structure, roughening or growth, or more length scale morphologies. Phase-field crystal method can be used to describe the solid crystal by atomic density field with periodic symmetry. The phase-field crystal method can be used to capture these features at atomic length scale from diffusion time scale effectively. some conclusions as follows:1Growth ratio of the epitaxial film is smaller during the early growth, and increasing with the evolution time; the solid-liquid interface will be more flat if the system releases more elastic energy during the growth later time even until last; the deeper super cooling temperature, the higher growth ratio in the later time; the "cusp" on the solid-liquid interface is deeper if the supercooling temperature is higher; the annihilation of misfit dislocations will emerge at the deeper supercooling.2If the mismatch between substrate and epitaxial film is smaller, the critical height of the film will be thicker, and the density of misfit dislocations is lower; the fluctuation of the solid-liquid interface will be smaller if the excess elastic energy is less at the last.3The orientation of epitaxial film will incline to substrate and there is a linear relationship between the tilting angle of film and substrate, and the morphologies of solid-liquid interface will be more rough when the substrate tilt is smaller or larger.4The fluctuation of last solid-liquid interface is more serious which curvature is larger on convex substrate-film interface; on the concave substrate-film interface, the dislocations in the epitaxial film move to the substrate along the radial direction of the substrate-epilayer interface.