Surface Oxidation of Quantum Wires and Dots—Explaining Photoluminescent Blue Shift in Nanocrystalline Silicon

Nanocrystalline structures were produced by electrochemical etching of boron-doped crystalline silicon in the presence of a strong acid. The resulting films, a few microns in depth, exhibited strong photoluminescence under blue or ultraviolet excitation in laboratory room conditions. Emission spectra were recorded using a spectrofluorometer with excitation wavelengths from 450 nm to 250 nm for both fresh and aged samples. The data showed broad photoluminescence (PL) peaks centered around 650 nm with distinct structural features. A blue shift in the PL peak maxima was observed with increasing excitation photon energy, more pronounced in aged samples compared to fresh ones. These results are interpreted using the Smart Quantum Confinement model, which considers contributions from silicon quantum wires (QWs) and quantum dots (QDs).