INTERDIFFUSION AND STRAIN RELAXATION IN (SIMGEN)P SUPERLATTICES

We report an x-ray diffraction study of interdiffusion and strain relaxation in (SimGen)p short-period superlattices. An interdiffusion coefficient Dλ was determined by monitoring, as a function of time, the decay upon annealing of the first order 000 satellite peak arising from the compositional modulation of the superlattice. Strain relaxation was obtained from the shift of the 400 superlattice peak on annealing. In the early stage of annealing the low angle satellite exhibited a rapid nonexponential decay after which a slower exponential decay was observed indicating a larger initial interdiffusion coefficient. This enhancement was correlated with the presence of strain and it disappeared upon relaxation. Diffusion was faster in structures alternating thin Si and thick Ge layers suggesting that migration of Si into Ge is the dominant diffusion process.