Enhancement of erbium photoluminescence by substitutional C alloying of Si

Photoluminescence (PL) at 1.54 μm of erbium-doped Si1−yCy alloys grown by molecular beam epitaxy (MBE) has been analyzed depending on sample temperature, excitation density, and growth conditions. Erbium activation raises with increasing incorporation of substitutional carbon compared to interstitial carbon. For [Er]=4.5×1019 cm−3 and y=0.1% maximum PL output at 1.54 μm was achieved for growth temperatures at 430 °C. Additional annealing could further enhance PL intensity at 1.54 μm. For increasing sample temperature a decrease of PL intensity with two characteristic activation energies around 100 and 10–20 meV is observed, which results in quenching of PL intensity at lower temperatures for Si:Er:C layers compared to Si:Er:O layers. PL spectra show different fine structure for oxygen and carbon codoping by MBE or ion implantation, higher efficiency, and lower PL background for MBE-grown samples in contrast to ion-implanted layers.