An effective compliant substrate was fabricated for the growth of high-quality relaxed SiGe templates, by synthesizing a 20% B2O3 concentration borosilicate glass (BSG) in the silicon on insulator wafers. Substrates with 5%, 10%, and 20% B2O3 were used for 150 nm Si0.75Ge0.25 epitaxy. Double-axis x-ray diffraction measurements determined the relaxation and composition of the Si1-x Gex layers. Cross-sectional transmission electron microscopy was used to observe the lattice of the SiGe epilayer and the Si substrate, dislocation density, and distribution. Raman spectroscopy was combined with step etch to study the samples. The strain sharing effect of the 20% BSG substrate was demonstrated. Thus, we concluded that this compliant substrate is a highly promising candidate for the growth of low-dislocation relaxed SiGe layers.