Control of Semiconductor Epitaxy by Application of an External Field

Abstract : With the growing demand for reduction in size of semiconductor devices, understanding the chemistry and physics at the atomistic level is becoming an essential part of the design of devices based on electronic materials. One of the major challenges in this area is to obtain desired surface morphology of a thin film by controlling external parameters, such as temperature and pressure. The smoothness of a thin-film surface depends on the rate of surface diffusion of the adatoms during the growth process. Enhancing surface diffusion can lead to a smooth film. In other words, the rate of surface diffusion will depend on how strongly the adatoms bind to the surface. Reducing the binding energy of the adatoms with the surface will result in enhanced surface diffusion. In the present work, the authors show how application of an external field can be used to control binding energy. First-principle calculations were performed to calculate binding energies at different field strengths and orientations, followed by Kinetic Lattice Monte Carlo simulations to obtain surface microstructure. Using the above methods, the authors established a correlation between the external field (strength and orientation) and the microstructure of GaN thin film in MBE process. They have shown that by controlling the strength and orientation of the external field one can obtain GaN thin film with the desired roughness. (25 figures, 9 refs.)