The effects of Si surface oxidation on Si–Ge interdiffusion in epitaxial heterostructures were presented. Single crystal Si1−xGex/Si1−yGey superlattices, with a nominal Ge composition of 8.5at%, were grown by low-pressure chemical vapor deposition onto Si(001) substrates. An epitaxial Si cap, which was partially consumed during post-deposition annealing in dry O2, was grown onto these superlattices. An enhancement of Si–Ge interdiffusion kinetics was observed for the case of oxidation annealing when compared to inert atmosphere annealing. X-ray multilayer scattering measurements were used to quantify the effects of non-equilibrium point defect concentrations created during Si oxidation on the interdiffusivity of Si and Ge at 770 to 870C. The interdiffusivity at this Si–Ge composition, as determined by analysis of the X-ray multilayer satellite intensity decay after annealing, could be described by:

D (cm2/s) = 1.32 x 100 exp[-3.99(eV)/kT]

The extent of the interdiffusivity enhancement caused by Si surface oxidation was significantly less than that reported for Si self-diffusion. This suggested a smaller interstitial-mediated component for Si–Ge interdiffusion than for Si self-diffusion.

Oxidation-Enhanced Interdiffusion in Si1-xGex/Si1-yGey Superlattices. N.Ozguven, P.C.McIntyre: Applied Physics Letters, 2007, 90[8], 082109