Characterization and reduction of twist in Ge on insulator produced by localized liquid phase epitaxy

Abstract

Conditions for producing high-quality localized Ge-on-insulator film stacks on Si substrates by liquid phase epitaxy are discussed. In particular, we have found that the resulting Ge crystal planes have a tendency to exhibit a twist about the long axis of the crystal. If the wafer is heated much above the Ge melting temperature, this twist can be quite large (∼10°). The twist can be minimized by heating to just above the melting temperature and by using thicker Ge films. In spite of this twist, the Ge regions on top of the insulating Si3N4 are observed to be free of dislocations and stacking faults.