Thermal stability of strained Si on relaxed Si_1-xGe_x buffer layers

The thermal stability of strained Si on relaxed Si1-xGex structures annealed at 1000 °C was investigated using high-resolution x-ray diffraction, Raman spectroscopy and transmission electron microscopy. Interdiffusion at the Si/Si1-xGex interface is negligible for annealing times <30 sec and is independent of the initial Si layer thickness and the composition of the Si1-xGex layer. In all cases the Si layers remained nearly fully strained, but a significant density of misfit dislocations was seen in layers that exceeded the critical thickness for dislocation glide. The Si layer thickness could be measured for layers as thin as 7 nm.