We measured the photoluminescence (PL) spectra of a series of Ge n quantum wells as a function of temperature, from 2K to 50K. The PL spectra at 2.1K are dominated by broad emission lines, which can be interpreted as recombination across the indirect gap of the Si/Ge microstructure and are strongly influenced by the interface morphology of each sample. Beyond T <img src="http:/img/fbpe/bjp/v29n3/547i1.gif" alt="547i1.gif (50 bytes)"> 15K, all samples show identical spectra in which the broad structures are replaced by thin, strong lines. We interpret these changes as a quenching of the recpmbination across the gap PL of the microstructure and the appearance of defect-related peaks from the Si substrate.
w), linewidths (G) and relative intensities (with that of the line at 0.767 eV taken arbitrarily at 100) of the PL lines appearing in the T = 16K spectra of the front and back ends of the Si/Ge5/Si sample. The relative intensities have been corrected by the response of the experimental set up [13]. The last column gives the assignment of similar lines appearing in the PL spectra of bulk Si as listed in ref. [15]. 