Patterned strained semiconductor substrate and device

A method for forming an electrical device, the method comprising:

• etching a recess through a pad oxide layer and into a substrate;
• forming an insulating layer on sidewalls and a bottom of the recess;
• removing a portion of the insulating layer from the bottom of the recess;
• forming a buffer layer in the recess and between portions of the insulating layer, wherein the buffer layer is in contact with a portion of the substrate and has a lattice constant/structure mismatch with the substrate;
• forming a relaxed layer in the recess and between the portions of the insulating layer, wherein the relaxed layer is in contact with the buffer layer;
• forming a strained layer in the recess and between the portions of the insulating layer, wherein the strained layer is in contact with the relaxed layer;
• stripping the pad oxide layer;
• planarizing the substrate;
• forming a strained device in the strained material;
• and
• forming a non-strained device in the substrate adjacent to the strained material.