Thermal stability of the [(Si) <i>_m</i>/(Ge)<i>_n</i>]<i>_p</i> superlattice interface

The structure of [(Si) <i>_m</i>/(Ge)<i>_n</i>]<i>_p</i> superlattice interfaces and the onset of relaxation and interdiffusion initiated by annealing have been investigated with the use of extended x-ray-absorption fine structure and Raman scattering. For the as-grown material, the Ge-Ge bond length (0.2409 nm) was equal to that calculated for a fully strained Ge layer (0.2412 nm) while the Si-Ge bond length was significantly shorter. The results show conclusively that substantial intermixing along with partial relaxation of the Ge-Ge bonds occurs even for the shortest anneal at 700 °C.