Photoluminescence and absorption in multi-energy Ge implanted type III silica

Silica samples were implanted at multiple energies with Ge ions, which resulted in an implanted layer, ∼2.4μm in length starting ∼0.8μm below the surface and in which the atomic percent of Ge ranged from ∼0.02% to ∼0.1%. Optical absorption was measured from 2.7 to 6.4eV and in all spectra a local maximum at 5.0eV and a shoulder at 5.9eV were observed. Based on the bands reported in the literature we assumed that Gaussian bands at 4.8, 5.01, 5.17, 5.88, and a band greater than 6eV determined by the fitting process comprised the observed spectra. Using Gaussian functions as basis states, fits to the data were performed yielding amplitudes for each band. An additional band at 5.54eV was required to fit the spectra. This band’s amplitudes were correlated with the Ge concentration. Photoluminescence (PL) measurements were made from 2.6 to 4.6eV using excitation energies from 4.5 to 5.5eV. PL bands at ∼4.4eV and ∼3.2eV were detected. The 4.4eV band intensity has a correlation coefficient of ∼1 with Si concentration. The band at 3.2eV has a correlation coefficient ∼1 with the concentration of Ge ions. A PL band at 2.7eV was not detected in either the Si or Ge implanted samples.