Ge composition in Si1-xGex films grown from SiH2Cl2/GeH4 precursors

Abstract

A simple model for the Ge composition in Si1-xGex films grown from SiH2Cl2/GeH4 precursors is developed on the basis of adsorption and desorption kinetics for the intermediate temperature range (600 degrees C < T < 900 degrees C). For this system, the solid phase composition of Ge, x, is related to the gas phase composition ratio of the two source gases, G, by x(2)/(1-x) = constantxG, which contrasts with the conventional relationship, x/(1-x) = constantxG, that is known for SiH4/GeH4 chemical vapor deposition. The proportionality constant depends not only on temperature but also on pressure. The model compares well with the experimental data in the literature.