Growth of Si1-x-yGexCy multi-quantum wells: Structural and optical properties

We have studied the optical properties and growth by rapid thermal chemical vapour deposition of multi-quantum well heterostructures based on the group IV elements Si, Ge and C. Si1-xGex/Si, Si1-x-yGexCy/Si, Si1-xGex/Si1-yCy and Si1-yCy/Si heterostructures were investigated by X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS), photoluminescence and Raman spectroscopy. Different features are observed depending on the growth temperature. At 575 degrees C, carbon and germanium are incorporated as expected, whereas at lower temperatures (550 degrees C), strong segregation occurs, as indicated by the decrease in the number of periods of the heterostructure observed by SIMS and XRD. Photoluminescence identifies a defect Line associated with carbon and oxygen. Raman spectroscopy shows that, although carbon compensates for the external strain, the energy of the Si-Ge vibration mode is only weakly modified.