Epilayers of Si0.7Ge0.3, with low threading dislocation densities, were grown onto Si(001) substrates over an intervening low-temperature Si buffer. When compared with conventional compositionally-graded buffers, this had the advantage of producing a lower threading dislocation density, requiring a smaller thickness for the desired degree of relaxation, and giving a smoother surface. The experimental evidence suggested that an anomalous relaxation mechanism was involved.

J.H.Li, C.S.Peng, Y.Wu, D.Y.Dai, J.M.Zhou, Z.H.Mai: Applied Physics Letters, 1997, 71[21], 3132-4