LOW-TEMPERATURE EPITAXIAL-GROWTH OF SILICON AND SILICON-GERMANIUM ALLOY BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION

Abstract

Low-temperature epitaxy of silicon and silicon-germanium alloy via an ultrahigh-vacuum chemical vapor deposition system was investigated. Bistable conditions were observed for silicon epitaxial growth performed within the temperature range of 550 degrees C to 800 degrees C. The activation energy of the SiGe growth rate was found to decrease as the germanium composition increased. The germanium atomic molar fraction in these epitaxial layers was tightly controlled by a computer-controlled gas source switching system. Si/SiGe superlattice structures of 20-period 5 nm Si/12 nm SiGe layers were grown to demonstrate the excellent controllability of this growth technique.