A. Polman

Optical doping of waveguide materials by MeV Er implantation

Implantation of MeV erbium ions into micron‐thick silica and phosphosilicate glass films and 1200‐A‐thick Si3N4 films is studied with the aim of incorporating the rare‐earth dopant on an optically active site in the network. Implantation energies and fluences range from 500 keV to 3.5 MeV and 3.8×1015 to 9.0×1016 ions/cm2. After proper thermal annealing, all implanted films show an intense and sharply peaked photoluminescence spectrum centered around λ = 1.54 μm. The fluorescence lifetime ranges from 6 to 15 ms for the silica‐based glasses, depending on annealing treatment and Er concentration. Silicon nitride films show lower lifetimes, in the range <0.2–7 ms. Annealing characteristics of all materials are interpreted in terms of annealing of ion‐induced network defects. These defects are identified using photoluminescence spectroscopy at 4.2 K. Concentration quenching, diffusion and precipitation behavior of Er is also studied.

Local structure around Er in silica and sodium silicate glasses

Abstract Extended X-ray absorption fine structure (EXAFS) and photoluminescence (PL) measurements have been performed on three different Er-doped glasses: silica and sodium silicate doped with Er in the molten phase, and silica doped by MeV ion implantation. All samples show a luminescent transition centered around a wavelength of λ = 1.54 μ m, corresponding to an intra-4f transition of Er 3+ . EXAFS data show that the Er ions have about six O first neighbors, at a distance of 2.26 A in all systems. Both silica glasses show a second-neighbor ErSi shell at 3.11 A which is not seen in the sodium silicate glass. This difference is reflected in a difference in the PL spectra. The ErO shell in the silica glass shows 0.01 A 2 more disorder than that in the Na-loaded material. These findings are rationalized in terms of the network-modifying effect of Na. Both EXAFS and PL show no significant differences between silica samples prepared in the molten phase or by implantation. At an Er concentration of ∼1 at.%, no direct ErEr bonds are observed.

1.54 μm room‐temperature luminescence of MeV erbium‐implanted silica glass

MeV erbium implantation doping of 10‐μm‐thick silica glass films on a Si substrate is studied with the aim of incorporating the rare‐earth dopant on an optically active site in the silica network. As‐implanted samples (3.5 MeV, 5×1015 Er ions/cm2) show a strong luminescent transition at a wavelength of 1.54 μm, even at room temperature, corresponding to an intra‐4f transition of Er3+. Thermal annealing at temperatures up to 900 °C increases the luminescence intensity by a factor of 2 to 3. For temperatures above 1000 °C the intensity decreases drastically as a result of Er precipitation. The lifetime of the excited state is in the order of 10 ms. Photoluminescence studies at 4.2 K are used to identify implantation‐induced damage.

Impurity trapping and gettering in amorphous silicon

Palladium atoms have been gettered from the bulk of an amorphous Si (a‐Si) layer to an ion‐implanted surface region. The 2.2‐μm‐thick a‐Si layers, formed by MeV Si implantation, were implanted with 500 keV Pd and then annealed at 500 °C. This produces a complete redistribution of Pd within the layer and relaxation or substantial defect annihilation in the a‐Si. Subsequently, defects were introduced into the surface region (∼4000 A) by 200 keV Si implantation at various doses. After low‐temperature diffusion at 250 °C, Pd atoms are gettered in the Si‐implanted region. At low Si fluences, Pd decorates the Gaussian depth distribution of the ion‐induced damage, while at higher a saturation is reached in the gettering profile. The ion damage is calculated to saturate when 2% of the target Si atoms are displaced by atomic recoils. Below saturation, the displacement of two Si atoms is calculated to produce one Pd trapping site.

Photoluminescence and structural characterization of MeV erbium-implanted silica glass

Abstract Suprasil glass (amorphous SiO2) has been implanted with 2.9 MeV Er ions at fluences of 3.4 × 1015and 3.4 × 1016ions/cm2. Photoluminescence spectra of implanted samples show a clear luminescent transition around λ = 1.54 μm, corresponding to an intra-4f transition of Er3+. Fluorescence decay times are in the range 1–8 ms, depending on implantation fluence and annealing treatment. UV absorption and IR reflection spectroscopy are employed to characterize beam-induced defects in the silica network. The results indicate that defects in the silica network play an important role in the energy transfer processes in the Er: silica system.