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 SiSUB1-x/SUBGeSUBx/SUB 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 10SUP6/SUPcmSUP2/SUP. The approach begins with the growth of a pseudomorphic or nearlypseudomorphic SSUB1-x/SUBGeSUBx/SUB 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 SSUB1-x/SUBGeSUBx/SUB interface, parallel to the Si(001) surface