Optical properties of bulk and multi-quantum well SiGe:C heterostructures

We have investigated optical properties of SiGe:C layers deposited on Si(100). Bulk and multi-quantum well heterostructures were grown by rapid thermal chemical vapor deposition using methylsilane as carbon precursor, The optical properties are analyzed as a function of the structural properties of the alloys. The photoluminescence of these structures exhibits two features: deep level photoluminescence associated with localized states and band-edge recombination which gives an indication of the band gap variation due to carbon incorporation in substitutional sites, in the case of multi-quantum well heterostructures, we report on an enhancement of the radiative recombination associated with silicon at room temperature in presence of Si1-xCx layers. The strain compensation induced by carbon in SiGe, which is evidenced by X-ray diffraction, is compared to the Raman spectroscopy of the vibration modes of the alloy.