KINETICS OF INTERDIFFUSION IN STRAINED NANOMETER PERIOD SI/GE SUPERLATTICES STUDIED BY RAMAN-SCATTERING

Intermixing time ti and interdiffusion coefficients D of nanometer periods Si/Ge strained layer superlattices (SLSs) were measured by Raman scattering technique. Si12Ge12 and Si19Ge9 SLSs have been annealed in the temperature range 760-900°C during various time intervals. The observed D and ti follow the Arrhenius-like behavior with different activation energies ΔE=1.78±0.15 eV and 3.94±0.15 eV and pre-exponential factors D=2×10-10 cm2 s-1 and 0.7 cm2s-1, respectively, for the Si12Ge12 and Si19Ge9 SLSs. D, ti, ΔE, and D0 are strongly affected by the changes of the SLS layer thickness, and strain. An explanation of the experimental observations is proposed in terms of the kinetic electron-related theory of atomic diffusion in solids. The observed variations of ΔE and D0 are related to the material parameters, which are characterized by picosecond atomic and electronic phenomena in nanometer regions, in good agreement with the observations.© 1995 American Institute of Physics.