Growth and characterization of Si/SiGe microstructures on patterned Si substrates using gas source molecular beam epitaxy

SiGe/Si multi-quantum wells (MQWs) were grown on ridges formed on terraces between parallel V-grooves along the [110] direction on Si(001) surfaces. The structures were characterized using photoluminescence (PL), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM micrographs indicate that the morphology of the low index side walls of the ridges is significantly better than that of the etched V-grooves. Cross-sectional TEM studies show that SiGe/Si MQW structures are formed at the top of the ridges, which provides possible confinement for quantum wires. Compared with MQWs formed on an unpatterned (001) surface, PL emission corresponding to the no-phonon (NP) and transverse optical (TO) phonon assisted peaks is shifted to higher energy. The position of these peaks appears to be independent of the size of the ridge.