Papers by Keyword: Erbium

Abstract: Er3+-doped fluoride glass ceramics planar waveguides containing LaF3 or binary LaF3- ZrF4 nanocrystals have been fabricated by Physical Vapour Deposition (PVD). A quantitative analysis of the photoluminescence for the 1.5μm emission band of Er3+ ions has demonstrated that erbium ions are partitioned in both crystals and vitreous phase; the solubility of Er3+ in the segregated LaF3 nanocrystals can reach 30 mol% and the emission bandwidth has been found to be greater than that of the precursor glass (71nm at the half-height width). In order to increase the luminescence of Er3+, codoping with Yb3+ and Ce3+ has been investigated. The high Er3+ concentration and spectral width could make this nanostructured fluoride material suitable for planar amplifier in the C telecommunication band.

Abstract: For the first time, nano-scale rods of NaLaxYb9-x(SiO4)6O2 (x=1,3,5,7,9) crystals (NLS) activated with Er3+ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P63/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er3+ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.

Abstract: We present the details of the sol-gel processing used to realize inverse silica opal, where the silica was activated with 0.3 mol% of Er3+ ions. The template (direct opal) was obtained assembling polystyrene spheres of the dimensions of 260 nm by means of a vertical deposition technique. The Er3+-activated silica inverse opal was obtained infiltrating, into the void of the template, the silica sol doped with Er3+ ions and subsequently removing the polystyrene spheres by means of calcinations. Scanning electron microscope showed that the inverse opals possess an fcc structure with a air hollow of about 210 nm. A photonic band gap in the visible range was observed from reflectance measurements. Spectroscopic properties of Er3+activated silica inverse opal were investigated by photoluminescence spectroscopy. A bandwidth of 21 nm was measured for the 4I13/2 → 4I15/2 transition of Er3+ ions upon excitation at 514.5 nm. The luminescence decay curve of the 4I13/2 metastable state of the Er3+ ions presents a lifetime τ = 16.8 ± 0.1 ms giving a very high quantum efficiency of the fabricated system. Core-shell Er3+-activated silica spheres, where the core is the silica sphere and the shell is an Er2O3-SiO2 coating is proposed as a possible route for opal fabrication. For core-shell system a quantum efficiency of about 70% was estimated.

Abstract: Si and Er co-doped SiO2 films were fabricated by radio-frequency (RF) magnetron sputtering technique with a Si-Er-SiO2 target. The optical gain of 0.7 dB/cm was confirmed by the direct pumping of Er3+ using the laser diode (LD) of 980 nm in wavelength and 60 mW in output power. On the contrary, the pumping Si-nanocrystals by the Hg lamp 365 nm (1.5 W/cm2) induced the absorption loss above 1.48 μm region in wavelength, which was attributed to the free carrier absorption of Si-nanocrystals.

Abstract: We have obtained Er-doped ZnO thin film in a micropattern of reverse trapezoids processed on Si substrate by sputtering and ultrafine polishing techniques. Near-infrared light emission was detected successfully from the thin film filling a single micropit with 10 μm square. Transmission electron microscopy (TEM) observation showed epitaxial growth of ZnO crystals along the curvature of the micropit.

Abstract: We have fabricated GaInP/Er,O-codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) light-emitting diodes (LEDs) and successfully observed 1.5 µm electroluminescence (EL) due to an Er-2O center under forward bias at room temperature. Er excitation cross section by current injection decreased with increasing GaAs:Er,O active layer thickness, implying reduced diffusion length of injected carriers in the active layer. Carrier dynamics in GaAs:Er,O have also been investigated by means of a pump and probe reflection technique. Time-resolved reflectivity of GaAs:Er,O exhibited a characteristic dip after a steep decrease to negative in less than 10 ps. The analysis of the characteristic dip revealed short lifetime in range of ps for photoexcited carriers. The extremely short lifetime is quite coincident with the reduced diffusion length of injected carriers, and suggests that a trap induced by Er and O codoping would play an important role in dynamics of nonequilibrium carriers in GaAs:Er,O.

Abstract: Structural defects in Si:Er layers grown by molecular beam epitaxy have been studied by transmission electron microscopy. Two kinds of second phase precipitates are the main defects in the layers with Er concentration ≥ 2х1019 cm-3: ball-shaped precipitates (4-25 nm) of metallic Er localized at the layer-substrate interface and platelet precipitates of ErSi2 extending through the whole layer. We studied the effect of Er concentration (8х1018 - 4х1019 cm-3) and growth temperature (400 - 700°C) on the defect generation. The peculiarities of defect generation in MBE Si:Er layers implanted with B+ ions were also studied.

Abstract: The impact of strong neutron absorption on data analysis and the comparison of two different absorption corrections for neutron diffraction data implemented in the GSAS Rietveld code are the foci of this work. We investigated the effect of absorption on the texture and the thermal motion parameter for rolled elemental foils. The orientation distribution functions (ODF) of rolled foils of dysprosium and erbium metals were determined from neutron time-of-flight data patterns collected on HIPPO at LANSCE. Both Dy and Er are strong absorbers for thermal neutrons with absorption cross-sections of 994 barns for Dy and 159 barns for Er at l = 1.8 Å. Various stacks of foils of each material, along with combinations of absorbing and less-absorbing foils, were measured. The patterns were analyzed using the GSAS options for Debye-Scherrer and linear absorption models, as well as without an absorption correction. Discrepancies between refined and expected “true” values of crystallographic parameters if absorption is not taken into consideration are discussed.

Abstract: Several SiC bulk crystals were grown with erbium and ytterbium as doping materials. Erbium contents determined by secondary ion mass spectroscopy (SIMS) ranged from 1.2 · 1014 cm-3 to 1.04 · 1015 cm-3, while ytterbium contents were below SIMS detection limit. Photoluminescence (PL) investigations of the characteristic 4f-4f-transition lines revealed a reduced luminescence yield in highly nitrogen and aluminum co-doped samples. Also, samples without intentional co-doping grown on the C-face showed less luminescence intensity than those grown on the Si-face. A stabilizing effect of erbium doping on the 4H polytype was observed.