A multiscale model of the plasma assisted deposition of crystalline silicon

Abstract

Silicon is a promising material for solar cells and optical devices. Among the different growth techniques, Plasma Enhanced CVD (PECVD) attracts particular interest allowing to obtain high quality deposition at significant rates and low substrate temperatures. Controlling the film morphology is key for improving the material optoelectronic properties. In order to be able to relate growth rates and quality of the deposited material to the plasma operating conditions we have developed a detailed plasma-reactor model. The solution of mass, momentum and energy conservation equations in a 2D domain is considered, and eventually coupled to the solution of a discharge model based on a simplified gas phase chemistry. The main novelty of this model are the detailed gas phase and surface kinetic schemes developed. The gas phase model comprises about 30 chemical species involved in more than 80 reactions. Surface reaction probabilities were calculated based on a fully atomistic, dynamical approach. The predictive power of the model against experimental data is demonstrated, and the role of various radicals and ions in determining the film growth is discussed.