Composition Analysis of Ge Graded Si<sub>1-x</sub>Ge<sub>x</sub> Alloy Films by Capacitance-Voltage Method

Abstract

Capacitance-voltage method was used to analyze composition of the Si1-xGex alloy films with a stochiometry gradient of Ge, which were epitaxially grown on Si (100) substrate by chemical vapor deposition. Using the capacitance characteristics of Si1-xGex/Si obtained by applying a reserve bias to the Hg electrode probe, the contact barrier height for Hg/Si1-xGexjunction and Si1-xGex/Si junction, and band gap of SSi1-xGex were estimated respectively. With the band gap of Si1-xGex, composition of Si1-xGex in Hg/Si1-xGex junction and Si1-xGex/Si junction were further obtained. Because analyzed Si1-xGex was formed through bilateral inter-diffusion of Si into the epilayer and Ge into the substrate during the deposition, Ge distribution from surface to substrate in Si1-xGex alloy films can be figured out by fitting to diffusion exponential function. The Ge distribution acquired this way was in accordance with the depth profile by auger electron spectrum.