Near-Band-Edge Photoluminescence from PseudomorphicSi1−yCy/SiQuantum Well Structures

Band edge related photoluminescence (PL) is observed from ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y/\mathrm{Si}$ multilayer structures at low temperature. High quality samples were grown pseudomorphically on Si substrates by solid source molecular beam epitaxy. A bound exciton no-phonon line and its Si-Si TO phonon replica are observed at energies which decrease linearly with increasing C content. In 52 Å thick S${\mathrm{i}}_{0.984}$ ${\mathrm{C}}_{0.016}$ alloy layers the PL redshift is about 100 meV, compared to pure Si. The PL shifts to higher energy for decreasing ${\mathrm{Si}}_{1-y}{\mathrm{C}}_y$ layer width due to the quantum confinement of carriers. The decrease in PL energy observed for decreasing Si barrier layer width implies that neither electrons nor holes are localized in the Si layers.