OBLIQUE ROUGHNESS REPLICATION IN STRAINED SIGE SI MULTILAYERS/

The replication of the interface roughness in SiGe/Si multilayers grow n on miscut Si(001) substrates has been studied by means of x-ray refl ectivity reciprocal space mapping. The interface profiles were found t o be highly correlated and the direction of the maximal replication wa s inclined with respect to the growth direction. This oblique replicat ion is explained by the influence of the inhomogeneous strain distribu tion around step bunches. The formation of step bunches is described b y a kinetic step-how model based on the work by Tersoff et al. [Phys. Rev. Lett. 75, 2730 (1995)]. We have generalized this model by taking into account local variations of the in-plane strain. The angle of obl iqueness deduced from these calculations agrees very well with the exp erimental findings.