Epitaxial Crystallization of Ge on Si Using Evaporation and Recrystallization Techniques

Abstract

ABSTRACTGermanium films have been epitaxially crystallized on silicon substrates using the electron-beam evaporation technique and the laser! strip-heater recrystallization technique. Epitaxy was achieved either directly on Si surfaces or laterally on oxide/nitride-coated Si wafers. Evaporated Ge epi-layers were mirror-smooth and were found to be in excellent crystal quality. The recrystallized Ge on Si were also found to be good crystal, but showed somewhat roughened surface morphology. In both cases, the Ge near the Ge/Si interface is heavily replete with misfit dislocations arising from 4% lattice mismatch between Ge and Si. The recrystallized Ge on insulator (GOI) showed no mismatch dislocations at the Ge/insulator interface but developed voids arising from Ge dewetting from the insulator surface. Twins have been observed to be the most prominent defects in recrystallized Ge, whether seeded or unseeded. The objective of this study is to achieve quality Ge layers that can be used as intermediate template to accomodate GaAs on Si.