Patent ID: 7494881

Claim:
A method for selecting a placement of misfit dislocations, the method comprising the steps of: forming a first layer over a substrate, the first layer having a first equilibrium lattice constant; forming a second layer over the first layer, the second layer having (i) a second equilibrium lattice constant different from the first equilibrium lattice constant, and (ii) a critical thickness at which a plurality of misfit dislocations form at an interface proximate the second layer; and defining at least one of a source and a drain region by introducing a plurality of dopants into a portion of the second layer, a bottommost portion of the source or drain region being disposed above the misfit dislocations at the interface, wherein the second layer has a thickness defining a distance between a top surface of the second layer and the misfit dislocations that form at the interface corresponding to the selected placement of misfit dislocations when the thickness is equal to or greater than the critical thickness, such that a device formed at least partially in the second layer is substantially free of misfit dislocations.