  Microstructure changes during annealing of nano-crystalline silver and
amorphous silicon multilayers (Ag/a-Si) have been studied by X-ray diffraction
and transmission electron microscopy. The dc-magnetron sputtered Ag/a-Si
multilayers remained stable even after annealing at 523K for 10h, and
microstructural changes occurred only above 600K. The degradation of Ag/a-Si
multilayers can be described by the increase of size of Ag grains, formation of
grooves and pinholes at Ag grain boundaries and by the diffusion of silicon
atoms through the silver grain boundaries and along the Ag/a-Si interfaces.
This results in thinning of a-Si layers, and in formation of Ag granulates
after longer annealing times.
