Observation and modeling of the initial fast interdiffusion regime in Si/SiGe multilayers

X-ray diffraction is used to probe interdiffusion in asymmetrically strained, low concentration Si/SiGe superlattices. The results are shown to be in good agreement with a model developed from literature data for Ge diffusion in SiGe alloys. Using this model, it is shown that the initial fast interdiffusion frequently observed in Si/SiGe superlattices results primarily from the concentration dependence of the activation enthalpy for SiGe interdiffusion. Time dependent strain relaxation is shown to play a discernible, but secondary role in the transition from fast to slow interdiffusion. The linear proportionality constant relating the activation enthalpy of SiGe interdiffusion to biaxial strain is found to be ∼19 eV/unit strain. © 2002 American Institute of Physics.