Relaxed sige layers on si or silicon-on-insulator substrates by ion implantation and thermal annealing

Abstract

A method to obtain thin (less than 300 nm) strain-relaxed SiGebuffer 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 10cm. The approach begins with the growth of a pseudomorphic or nearly pseudomorphic SiGelayer, 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 operating with this method is dislocation nucleation at He-induced platelets (not bubbles) that lie below the Si/SiGeinterface, parallel to the Si(001) surface.