In situ investigations of Si and Ge interdiffusion in Ge-rich Si/SiGe multilayers using x-ray scattering

Abstract

We have explored the thermal stability of strain compensated Si/SiGe(80%) multilayers grown pseudomorphically by molecular beam epitaxy on relaxed SiGe(50%) pseudosubstrates. The structures were annealed in situ and investigated using x-ray reflectivity and diffraction techniques at temperatures of about 800 °C. From fitting of the reflectivity and diffraction profiles at various annealing time, we extracted interdiffusion coefficients of the structure for several annealing temperatures. The activation energy and the pre-exponential factor of the interdiffusion coefficient in SiGe(50%) was obtained from the Arrhenius-like temperature dependence of interdiffusion coefficients. Our results confirm that the interdiffusion pre-exponential factor decreases exponentially with increasing Ge content and the activation energy decreases linearly for Ge contents from 0 up to 50%.