Substrate pit formation and surface wetting during thermal annealing of strained-Si/relaxed-Si0.78Ge0.22 heterostructure

Abstract

During the elevated-temperature thermal annealing of a strained-Si/relaxed-Si0.78Ge0.22 heterostructure, deep substrate pits penetrating into the relaxed-Si0.78Ge0.22 buffer were formed and the strained-Si surface was wetted by the Si and Ge atoms originating from the deep pits. The pit formation and surface wetting are presumably due to the decrease in the strained-Si surface energy, resulting in a reduction in the total energy. The strain of the remaining strained-Si layer situated away from the deep pits was slightly increased despite the increased relaxation of the SiGe buffer, which implies that the remaining strained-Si layer was morphologically stabilized by the SiGe wetting.