Enhancement of Strain Relaxation of SiGe Thin Layers by Pre-Ion-Implantation into Si Substrates

Abstract

Almost fully relaxed thin SiGe buffer layers that are essential for the growth of strained SiGe heterostructures are obtained by Ar ion implantation into Si substrates before SiGe molecular beam epitaxy (MBE) growth. The strain-relaxation ratio of the 100-nm-thick Si0.73Ge0.27 layers, which is much thinner than that of the conventional method, on the Si substrates implanted under appropriate conditions exceeds 90%. Strain relaxation is found to strongly depend on ion dose and energy, suggesting the role of implantation-induced defects in strain relaxation.