Blue-light emission from crystalline Si/silica core/shell nanowires

Si nanowires (NWs) have great potential for future applications in electronics, photonics, biology, and energy owing to their unique structural, electronic, and optical properties based on one-dimensional quantum confinement effects. Intensive research have been performed successfully for understanding the growth mechanism and the electrical properties of Si NWs but only a few studies have been reported on their luminescence properties without a comprehensive understanding of the light-emission mechanism. In this study, crystalline Si/silica (c- Si/SiO_x) core/shell NWs are produced by annealing Ni-coated Si-rich SiO_x (SRO) films at 1100 degC under a N₂ ambient. The room temperature photoluminescence (PL) spectra of the individual NWs have two major emission bands in the near UV (381 nm) and blue (435 nm) ranges at n_Si (Si concentration) = 43 at. %, whilst at nsi = 37 at. %, only blue band is observed. The photoluminescence behaviors are discussed based on the possible physical mechanism.