A review was presented of attempts to grow a new type of single crystal Si epitaxially on Si(111). The new single crystal Si was a superlattice of layers that had twinned and untwinned orientations with respect to the substrate, and was called a twinning superlattice. The Si twinning superlattices were grown using the fact that Si layers grown epitaxially on Si(111) √3 x √3-B have a twinned orientation with respect to the substrate

The conditions for growing twinned epitaxial layers were investigated, and it was clarified that the growth of twinned layers required a high surface B concentration and low densities of surface structural defects, such as steps and domain boundaries of the √3 x √3 reconstruction. The thermal stability of the twinned layers was also investigated, and it was clarified that the temperature at which the twinned layers were transformed into untwinned layers strongly depended upon the thickness. Additionally, a technique was established for measuring crystallographic orientations in surface regions in situ during growth. On the basis of these results, it was found to be possible to succeed in growing the Si twinning superlattice by repeated growth of Si with a unit thickness, and post-growth annealing.

Growth of Si Twinning Superlattice. H.Hibino, T.Ogino: Materials Science and Engineering B, 2001, 87[3], 214-21

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