A method of forming a relaxed SiGe-on-insulator substrate having enhanced
relaxation, significantly lower defect density and improved surface
quality is provided. The method includes forming a SiGe alloy layer on a
surface of a first single crystal Si layer. The first single crystal Si
layer has an interface with an underlying barrier layer that is resistant
to Ge diffusion. Next, ions that are capable of forming defects that
allow mechanical decoupling at or near said interface are implanted into
the structure and thereafter the structure including the implanted ions
is subjected to a heating step which permits interdiffusion of Ge
throughout the first single crystal Si layer and the SiGe layer to form a
substantially relaxed, single crystal and homogeneous SiGe layer atop the
barrier layer. SiGe-on-insulator substrates having the improved
properties as well as heterostructures containing the same are also
provided.