MODULATION WAVELENGTH DEPENDENCE OF THE INTERDIFFUSION IN AMORPHOUS Si/Ge MULTILAYER FILMS

Abstract

AbstractCompositionally modulated amorphous Si/Ge thin films with repeat lengths (wavelengths) between 4.8 nm and 5.83 nm have been prepared using ion beam sputtering. The interdiffusion coefficient was determined from the decrease in the (000) x-ray satellite intensities with annealing, and was found to be relatively large, so that it could easily be measured without crystallization occurring. The effect of copper and oxygen impurities was found to be negligible. The dependence of the interdiffusivity on the modulation wavelength is similar to that of an ordering system. The temperature and wavelength dependence in the range T = 550-630 K is described by Dλ = 1.47×10−10 m.s−1 exp(-l.6 eV/kT)(l-21.8/λ2(nm)). It is suggested that diffusion is governed by the breaking of one bond near a pre-existing dangling bond.