Stress and its Effect on Intermixing in Si1-xGex/Si Superlattices

Abstract

AbstractInterdiffusion behavior in long-period Si1-xGex/Si as a function of growth conditions and external stress is examined using x-ray diffraction and Raman Spectroscopy. Both symmetrically and asymmetrically-strained superlattices have been examined, and an activation energy for interdiffusion of 3.9 eV and 4.6 eV have been obtained, respectively. In addition, an enhanced interdiffusion has also been measured in an externally stressed asymmetric superlattice. In both cases, enhanced interdiffusion has been measured whenever the Si barrier layers experience tensile stress during annealing. The Raman spectroscopy supports this result, showing an enhanced Ge diffusion into the Si barriers when these barriers are put under tensile stress. This result will be discussed in terms of the kinetics of defect formation and motion in the strained Si barriers.