The fabrication of dislocation-free strain-relaxed SiGe-on-insulator layers was demonstrated as virtual substrates for strained Si-on-insulator metal–oxide–semiconductor field-effect transistors by forming SiGe-mesa structures and successive oxidation. A pseudomorphic Si0.9Ge0.1 layer on a Si-on-insulator layer was etched to form mesa structures. After the oxidation of the mesas, thin (< 100nm) Si0.85Ge0.15 mesa structures were formed on the buried oxide layer. It was found that the mesas with a diameter smaller than 3µm were almost completely relaxed after oxidation at 1200C, without generating any threading dislocations and cross-hatch patterns, which generally exist in the relaxed SiGe layers on bulk Si substrates.

Dislocation-Free Formation of Relaxed SiGe-on-Insulator Layers. T.Tezuka, N.Sugiyama, S.Takagi, T.Kawakubo: Applied Physics Letters, 2002, 80[19], 3560-2