Composition Analysis of Ge Graded Si1-xGex Alloy Films by Capacitance-Voltage Method
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.
Y. Yang et al., "Composition Analysis of Ge Graded Si1-xGex Alloy Films by Capacitance-Voltage Method", Advanced Materials Research, Vols. 383-390, pp. 7613-7618, 2012