Effect of thermal processing on mobility in strained Si/strained Si_(1-y)Ge_(y) on relaxed Si_(1-x)Ge_(x)(x

摘要

Annealing-effects on hole and electron mobility in dual-channel structures consisting of strained Si and Si_(1-y)Ge_(y) on relaxed Si_(1-x)Ge_(x) layers (x=0.3/y=0.6, and x=0.5/y=0.8) were studied. Hole mobility decreases sharply, but electron mobility is quite immune to annealing conditions of 800℃, 30 min or 900℃, 15 s. The hole mobility decrease is more severe in dual-channel structures with higher Ge contents. Hole mobility degradation is a direct result of Ge outdiffusion from the Si_(1-y)Ge_(y) layer, and the resulting decreased Ge content. Ge diffusion preferentially towards the Si_(1-x)Ge_(x) buffer layer, rather than the Si cap layer, is a reason that electron mobility is highly immune to such annealing.