GROWTH OF SI1-X-YGEXCY MULTIQUANTUM WELLS - STRUCTURAL AND OPTICAL-PROPERTIES

We have studied the optical properties and growth by rapid thermal che mical vapour deposition of multi-quantum well heterostructures based o n the group IV elements Si, Ge and C. Si1-xGex/Si, Si1-x-yGexCy/Si, Si 1-xGex/Si1-yCy and Si1-yCy/Si heterostructures were investigated by X- ray diffraction (XRD), secondary ion mass spectroscopy (SIMS), photolu minescence and Raman spectroscopy. Different features are observed dep ending on the growth temperature. At 575 degrees C, carbon and germani um are incorporated as expected, whereas at lower temperatures (550 de grees C), strong segregation occurs, as indicated by the decrease in t he 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 w eakly modified.