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

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 degrees 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%.