Electrical characteristics of thermal CVD B-doped Si films on highly strained Si epitaxially grown on Ge(100) by plasma CVD without substrate heating

Using an 84% relaxed Ge(100) buffer layer formed on Si(100) by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (CVD), influence of strain upon electrical characteristics of B-doped Si film epitaxially grown on the Ge buffer have been investigated. For the thinner B-doped Si film, surface strain amount is larger than that of the thicker film, for example, strain amount reaches 2.0% for the thickness of 2.2 nm. It is found that the hole mobility is enhanced by the introduction of strain to Si, and the maximum enhancement of about 3 is obtained. This value is higher than that of the usually reported mobility enhancement by strain using Si_{1 - x}Ge_x buffer. Therefore, introduction of strain using relaxed Ge film formed by ECR plasma enhanced CVD is useful to improve future Si-based device performance.