SiO2:Ge photoluminescence:: Detailed mapping of the excitation-emission UV pattern

Photoluminescence (PL) data on SiO2:Ge samples have been obtained at 9 and 300 K by synchrotron radiation excitation, achieving a detailed mapping of the emission/excitation pattern in the UV and VUV energy range. Emission/excitation PL data have been analyzed by means of two-variables Gaussian components. New PL features have been identified, clarifying the composite nature of the excitation structure. The analysis of the high-energy portion of the collected spectra confirms that the alpha and beta emissions possess several excitation channels. The overall pattern calls for at least three distinct types of PL centers to justify the observed PL components: at about 3.1 and 4.3 eV (excited at 7.3, 6.6, and 5.4 eV), at 4.4 eV (excited at 5.1 eV), and 2.9 and 3.9 eV (excited at about 7.0 and 4.7 eV). [S0163-1829(98)03304-9].