Growth and Characterization of Highly Tensile-Strained Ge on InxGa1-xAs Virtual Substrate by Solid Source Molecular Beam Epitaxy

Tensile-strained Ge is a promising material for Si-based optoelectronic integratod circuits and next-generation high-performance multifunction solar cells. We have grown highly tensile-strained Ge films on strain-relaxed InxGa1-xAs virtual substrates using solid-source molecular beam epitaxy. The tensile strain in a Ge film is controlled over a wide range from 0 40 to 1 55% by changing the In mole fraction in InxGa1-xAs buffer layers The 1 55% tensile strain achieved is much higher than previously reported values. These results demonstrate the usefulness of the InxGa1-xAs buffer method for investigating the properties of tensile-strained Ge. (C) 2009 The Japan Society of Applied Physics