Improved hole mobilities and thermal stability in a strained-Si strained- Si 1- yGe ystrained-Si heterostructure grown on a relaxed Si 1- xGe x buffer

Abstract

A dual channel heterostructure consisting of strained-Sistrained- Si1-y Gey on a relaxed Si1-x Gex buffer (y>x), provides a platform for fabricating metal-oxide-semiconductor field-effect transistors with high hole mobilities. Ge outdiffusion during high temperature processing steps from the strained- Si1-y Gey layer into the relaxed Si1-x Gex buffer reduces the hole mobilities in these heterostructures. We present a strained-Sistrained- Si1-y Gey strained-Si heterostructure on relaxed Si1-x Gex, in which the strained-Si layer between the strained- Si1-y Gey and relaxed Si1-x Gex reduces Ge outdiffusion. Improved hole mobilities in this heterostructure are also observed over similar dual channel heterostructures which could be a result of better hole confinement in the strained- Si1-y Gey layer of the proposed heterostructure. © 2005 American Institute of Physics.