Rare-Earth Doped Silicon-Rich Silica: Evidence for Energy Transfer between Silicon Microclusters and Rare-Earth Ions
- PDF / 424,095 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 98 Downloads / 165 Views
Abstract We report the fabrication of rare-earth doped silicon-rich silica thin films by PECVD. The films exhibit absorption edges in the visible region of the optical spectrum consistent with the presence of silicon microclusters. Weak visible photoluminescence due to silicon microclusters is observed. In addition, strong luminescence from the rare-earth ion is obtained even when excited away from characteristic absorption bands; indeed, the luminescence intensity is largely independent of excitation wavelength below 514 nm. We ascribe this to excitation of silicon microclusters followed by an efficient transfer of energy to the rare-earth ions. The very broad absorption of this material opens up the possibility for flashlamp-pumped optoelectronic devices. In addition, we report the fabrication of silicon-rich silica films by PECVD. We show that the optical properties of these films are consistent with the presence of silicon microclusters and show absorption spectra similar to those of the rare-earth doped silicon-rich silica samples. This supports the hypothesis that the principal absorbing species in the rare-earth doped films is microclustered silicon.
Introduction There is currently a great deal of interest in the optical properties of microcrystalline, amorphous and porous silicon [1-5], principally due to the technological implications for fabrication of visible light emitting devices. Although much of the work in this area concentrates on the generation of light by quantum size structures on silicon substrates (quantum 'dots' or 'wires'), there has recently been interest in the optical properties of silicon clusters dispersed in a silica matrix [ 1,2,61. A number of groups have reported light emission from silicon-rich silica (SiOx, x
Data Loading...
