Observations were made of strain relaxation in lattice-mismatched heteroepitaxial Si1–xGex layers, accompanied by a reduction in threading dislocation density. This occurred on a Si0.77Ge0.23 layer grown on top of alternating layers of Si0.77Ge0.23/Si0.76Ge0.23C0.01. The present scheme permitted the growth of a high-quality 85% relaxed Si0.77Ge0.23 layer with a threading dislocation density of ~104/cm2. The high-resolution transmission electron microscope results showed the presence of Si1–x–yGexCy domains (with x below 0.23 and y below 0.01) after annealing at 1000C. It was deduced that the formation of these domains assist the low threading dislocation density relaxation by releasing the epitaxial misfit strain as localized discrete strain and by blocking the propagation of misfit dislocations.

Low Dislocation-Density Strain Relaxation of SiGe on a SiGe/SiGeC Buffer Layer. L.H.Wong, J.P.Liu, C.Ferraris, C.C.Wong, M.C.Jonatan, T.J.White, L.Chan: Applied Physics Letters, 2006, 88[4], 041915 (3pp)