Aperiodic one-dimensional Si∕SiO2 Thue–Morse (T–M) multilayer structures have been fabricated in order to investigate both the band gap properties with respect to the system size (band gap scaling) and the omnidirectional reflectance at the fundamental optical band gap. Variable angle reflectance data have experimentally demonstrated a large reflectance band gap in the optical spectrum of a T–M quasicrystal, in agreement with transfer matrix simulations. We explain the physical origin of the T–M omnidirectional band gap as a result of periodic spatial correlations in the complex T–M structure. The unprecedented degree of structural flexibility of T–M systems can provide an attractive alternative to photonic crystals for the fabrication of photonic devices.
Er doped Si-rich SiO2 films were deposited through reactive RF magnetron co-sputtering and subjected to a single annealing step to simultaneously form silicon nanocrystals (Si-nc's) and activate the Er emission. Reference Er in stoichiometric SiO2 (Er:SiO2) films were deposited for comparison and the Er emission in the presence of Si-nc's was optimized with respect to the annealing temperature. The Er emission from Er in SiO2 containing Si-nc's (Er:SiO2+Si-nc) films is maximized at annealing temperatures between 600 °C and 800 °C, where the 1.54 μm emission is enhanced by more than two orders of magnitude relative to Er:SiO2 samples. Efficient energy coupling between Si-nc's and Er ions was demonstrated through excitation cross section measurements and non-resonant Er excitation experiments for samples annealed at temperatures as low as 600 °C. Since strong emission can be achieved from Er:SiO2+Si-nc films deposited through a standard CMOS process and annealed at temperatures below 700 °C, they can be used to fabricate CMOS compatible light
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