MECHANISM OF SILICON EPITAXY ON POROUS SILICON LAYERS

The mechanism of silicon epitaxy on porous Si(111) layers is investiga ted by the Monte Carlo method. The Gilmer model of adatom diffusion ex tended to the case of arbitrary surface morphology is used. Vacancies and pendants of atoms are allowed in the generalized model, the activa tion energy of a diffusion hop depends on the state of the neighboring positions in the first and second coordination spheres, and neighbors located outside the growing elementary layer are also taken into acco unt. It is shown that in this model epitaxy occurs by the formation of metastable nucleation centers at the edges of pores, followed by grow th of the nucleation centers along the perimeter and the formation of a thin, continuous pendant layer. Three-dimensional images of surface layers at different stages of epitaxy were obtained. The dependence of the kinetics of the epitaxy process on the amount of deposited silico n is determined for different substrate porosities. (C) 1998 American Institute of Physics.