An intense photoluminescence (PL) peaking near 0.9 eV is emitted by a single Si1−xGex nanometer-thick layer (NL) with x ≈ 8% incorporated into Si/Si0.6Ge0.4 cluster multilayers (CMs). The SiGe NL PL does not saturate in output intensity with up to 50 mJ/cm2 of excitation energy density, and it has nearly a 1000 times shorter lifetime compared to CM PL, which peaks at ∼0.8 eV. These dramatic differences in observed PL properties are attributed to different compositions and structures of the Si/SiGe NL and CM hetero-interfaces.