Time-Integrated and Time-Resolved Photoluminescence Properties of Si Nanocrystal/SiO₂ Multilayers Grown by Ion-Beam Sputtering

Fifty-period SiO2/SiOx multilayers (MLs) were prepared on Si wafers by ion beam sputtering deposition and subsequently annealed to form Si nanocrystals (NCs) in the SiOx layer. Timeintegrated (TI) and time-resolved photoluminescence (PL) spectroscopy was employed to study the exciton migration, the state-filling effect, and the carrier lifetime of the NC MLs. The peak shifts of the TIPL spectra reflect the temperature and the size dependences of the migration process. The PL intensities for different energy levels of quantum-confined NCs decay with a stretched exponential function, and the decay times are in the range of 20 160 μs, depending on the observation energy and the NC size, which are discussed based on the effects of the quantum confinement and the state-filling of NCs.