We demonstrate an approach for fabricating relaxed SiGe layers on Si substrate with low threading dislocation density using commercially available low-pressure chemical vapor deposition epitaxy systems. This approach involves a thin epitaxial buffer layer with a reversed Ge composition gradient, i.e., the Ge composition decreases from the Si substrate to the growing surface. On a 90 nm thick buffer, growth of SiGe layer with composition up to 32% Ge was demonstrated with a strain relaxation >80% and a threading dislocation density below 10(6) cm(-2). (C) 2004 The Electrochemical Society.