A METHOD FOR FORMING A RELAXED EPITAXIAL SI1-xGEx LAYER WITH A LOW-DENSITY OF THREADING DISLOCATIONS ON A SINGLE CRYSTALLINE SURFACE

摘要

: A method to obtain thin (less than 300 nm) strain-relaxed Si1-xGex buffer layers on Si or silicon-on-insulator (SOI) substrates. These buffer layers have a homogeneous distribution of misfit dislocations that relieve the strain, remarkably smooth surfaces, and a low threading dislocation (TD) density, i.e. less than 106cm2. The approach begins with the growth of a pseudomorphic or nearlypseudomorphic Si1-xGex layer, i.e., a layer that is free of misfit dislocations, which is then implanted with He or other light elements and subsequently annealed to achieve the substantial strain relaxation. The very effective strain relaxation mechanism operatiing with this method is dislocation nucleation at He-inducedplatelets (not bubbles) that lie below the Si/Si1-xGex interface, parallel to the Si(001) surface