Novel method to introduce uniaxial tensile strain in Ge by microfabrication of Ge/Si_(1-x)Ge_x structures on Si(001) substrates

摘要

We have proposed a novel method to form by microfabrication a uniaxial tensile strained Ge layer due to the elastic strain relaxation of a Si_(1-x)Ge_x buffer layer on a Si(001) substrate. A fully strain-relaxed Ge layer on a compressive strained Si_(0.60)Ge_(0.40) was epitaxially grown on Si(001) substrate and striped mesa lines were fabricated with a line width of 250 nm along the [110] direction. The strain of the Si_(0.60)Ge_(0.40) layer was found to be elastically relaxed only along the direction perpendicular to the lines and a uniaxial tensile strained Ge layer was thus formed. The value of tensile strain of the Ge layer is estimated to be 0.25%.