Achieving epitaxy and intense luminescence in Ge /Rb-implanted α-quartz
TL;DR: In this article, the luminescence properties of ion-beam doped silica and quartz depend sensitively on the ion species and fluence and the thermal processing during and after ion implantation.
Abstract: The luminescence properties of ion-beam doped silica and quartz depend sensitively on the ion species and fluence and the thermal processing during and after ion implantation. In an attempt to achieve high luminescence intensity and full planar recrystallization of α-quartz, we studied double Ge∕Rb-ion implantation, where the Rb ions serve as a catalyst only. Synthetic α-quartz samples were irradiated with 175 keV Rb ions and subsequently with 120 keV Ge ions with fluences of 1×1014–1×1016ions∕cm2 and postannealed at 1170 K in air. A comparative analysis of the epitaxy, migration of the implanted ions, and cathodoluminescence (CL) were carried out. The CL spectra exhibit three strong emission bands in the blue/violet range at 2.95, 3.25, and 3.53 eV, which were assigned to Rb- and/or Ge-related defect centers. For up to 1015 implanted Geions∕cm2, large fraction (75%) of the Ge atoms reach substitutional Si sites after the epitaxy.
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TL;DR: In this paper, synthetic ZrSiO4 and (mildly to strongly radiation-damaged) natural zircon samples were irradiated with 8.8 MeV 4He2+ ions and the maximum extent of the damage was observed in a shallow depth range approximately 32-33μm (8.8MeV He) and ~12-μm(30 MeV O) below the sample surface.
Abstract: Synthetic ZrSiO4 and (mildly to strongly radiation-damaged) natural zircon samples were irradiated with 8.8 MeV 4He2+ ions (fluences in the range 1 × 1013–5 × 1016 ions/cm2). For comparison, an additional irradiation experiment was done with 30 MeV 16O6+ ions (fluence 1 × 1015 ions/cm2). The light-ion irradiation resulted in the generation of new (synthetic ZrSiO4) or additional (mildly to strongly metamict natural samples) damage. The maximum extent of the damage is observed in a shallow depth range approximately 32–33 μm (8.8 MeV He) and ~12 μm (30 MeV O) below the sample surface, i.e. near the end of the ion trajectories. These depth values, and the observed damage distribution, correspond well to defect distribution patterns as predicted by Monte Carlo simulations. The irradiation damage is recognised from the notable broadening of Raman-active vibrational modes, lowered interference colours (i.e. decreased birefringence), and changes in the optical activity (i.e. luminescence emission). At very low damage levels, a broad-band yellow emission centre is generated whereas at elevated damage levels, this centre is suppressed and samples experience a general decrease in their emission intensity. Most remarkably, there is no indication of notable structural recovery in pre-damaged natural zircon as induced by the light-ion irradiation, which questions the relevance of alpha-assisted annealing of radiation damage in natural zircon.
34 citations
TL;DR: In this paper, the spontaneous formation of superconducting NiBi3 phase in thermally evaporated Ni-Bi bilayer films was reported, and the transition temperature and upper critical field remained unchanged upto an ion dose of 1'×'1014 ions/cm2.
Abstract: We report the spontaneous formation of superconducting NiBi3 phase in thermally evaporated Ni-Bi bilayer films. High reaction-diffusion coefficient of Bi is believed to drive the formation of NiBi3 during the deposition of Bi on the Ni film. Cross sectional transmission electron microscopy and glancing incidence X-ray depth profiling confirmed the presence of NiBi3 throughout the top Bi layer. Superconducting transition at ∼3.9 K, close to the bulk value, was confirmed by transport and magnetization measurements. The bilayers were irradiated with varying fluence of 100 MeV Au ions to study the robustness of superconducting order in presence of large concentration of defects. Superconducting parameters of NiBi3, such as transition temperature and upper critical field, remained unchanged upto an ion dose of 1 × 1014 ions/cm2. The diffusive formation of NiBi3 in Ni opens the possibility of studying superconducting proximity effect at a truly clean superconductor-ferromagnet interface.
31 citations
TL;DR: In this article, a survey of cathode-luminescence spectroscopy performed after ion implantation in α-quartz is presented, in connection with dynamic, laser-induced and chemical epitaxy of the surface layers amorphized during the ion irradiation.
Abstract: Optical functionality of materials used in devices is the basis of modern photonics. It depends on selected photoactive impurities or low-dimensional structures, which can be tailored by ion implantation. The present survey covers cathode-luminescence spectroscopy performed after Ge, Ba, Na, Rb and Cs ion implantation in α-quartz, in connection with dynamic, laser-induced and chemical epitaxy of the surface layers amorphized during the ion irradiation. The correlations, which emerged for various luminescence bands, ion species and thermal processing methods, allows one to classify the bands into ion-specific and intrinsic ones. The microstructural properties measured by ion beam analysis and transmission electron microscopy will be combined with the luminescence data, and the role of photoactive defects in quartz and nanoparticles of the implants will be discussed. The technologically most attractive case of double Rb/Ge implantation will be highlighted, which combines the achievement of full chemical epi...
15 citations
TL;DR: In this article, light-emitting centers in alkali-ion-implanted α quartz have been investigated with respect to the solid phase epitaxial growth of the ion irradiation induced amorphous zone.
Abstract: Light-emitting centers in alkali-ion-implanted α quartz have been investigated with respect to the solid phase epitaxial growth of the ion irradiation induced amorphous zone. Cathodoluminescence was studied under the conditions of chemical epitaxy in annealing the samples, implanted with 2.5×1016 50keV Na ions/cm2 or 175keV Rb ions/cm2, in O218 atmosphere in the temperature range of 673–1173K. In addition to the known intrinsic subbands at 2.40, 2.79, and 4.30eV, which previously were associated with specific defects in the silica matrix, a strong violet band at 3.65eV and a band at 3.25eV have been identified. Both are intimately correlated with the presence of the implanted alkali atoms and recrystallization process. With respect to the 3.25eV band reported in the literature, they are discussed to be correlated with the presence of nanoclusters in Si-enriched, and Ge- and Sn-implanted SiO2 structures.
8 citations
TL;DR: In this article, a systematic investigation of dynamic, chemical, and laser-induced solid phase epitaxy of α-quartz after ion implantation was carried out and the results showed that no full epitaxy was achieved, however, the optical properties of these samples were analyzed using cathodoluminescence spectroscopy.
6 citations
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TL;DR: In this paper, the spectroscopic properties, structure and interconversions of optically active oxygen-deficiency-related point defects in vitreous silica are reviewed.
Abstract: The spectroscopic properties, structure and interconversions of optically active oxygen-deficiency-related point defects in vitreous silica are reviewed. These defects, the E′-centers (oxygen vacancies with a trapped hole or 3-fold-coordinated silicons), different variants of diamagnetic `ODCs' (oxygen-deficiency centers), and their Ge-related analogs play a key role in the fiber-optic Bragg grating writing processes. The controversy surrounding the structural models for the Si- and Ge-related ODCs is discussed and the similarity between the bulk and surface point defects in silica is emphasized. The possible interconversion mechanisms between 2-fold-coordinated Si, neutral oxygen vacancies and E′-centers are discussed. The effects of glassy disorder have a profound effect on defect properties and interconversion processes in silica.
1,157 citations
295 citations
01 May 1985-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the gamma ray yield function of (p, αγ) and resonance reactions on semi-thick 19F, 23Na, 24,26Mg and 27Al targets were measured and used to calibrate the accelerating voltage and energy resolution of the new 500 kV heavy ion implanter at Gottingen.
Abstract: Gamma ray yield functions of (p, αγ) and (p, γ) resonance reactions on semi-thick 19F, 23Na, 24,26Mg and 27Al targets were measured and used to calibrate the accelerating voltage and energy resolution of the new 500 kV heavy ion implanter at Gottingen. The energy spread of the proton beam was found to vary linearly with the accelerating voltage from ΔE(200 keV) = 55 eV fwhm to ΔE(500 keV) = 105 eV; it is made up by a 0.012% high voltage ripple and the Doppler broadening of the resonances due to the thermal motion of the target nuclei. A long term stability of the proton energy of Applications of the accelerator for the remeasurement of some resonance energies and widths and for depth profiling of light implanted ions in metals by the resonance broadening method will be briefly discussed.
293 citations
TL;DR: In this paper, a review of applications of cathodoluminescence scanning electron microscopy in the assessment of optical and electronic properties of semiconductors is presented, including information on band structure and impurity levels derived from spectroscopic cathodescence, analysis of dopant concentrations at a level which is in some cases several orders of magnitude better than x-ray microanalysis.
Abstract: This paper reviews applications of cathodoluminescence scanning electron microscopy in the assessment of optical and electronic properties of semiconductors. The assessment includes, for example, information on band structure and impurity levels derived from spectroscopic cathodoluminescence, analysis of dopant concentrations at a level which is in some cases several orders of magnitude better than x‐ray microanalysis, and mapping of carrier lifetimes and defects. Recent advances in both the various cathodoluminescence techniques and the processes leading to electron‐beam‐induced luminescence in semiconductors are reviewed. Possible future trends are also discussed.
226 citations
TL;DR: In this paper, it was shown that the observed visible luminescence in Xe+ -implanted samples is not due to the radiative recombination of quantum-confined excitons in Ge nanocrystals.
Abstract: Synthesis of Ge nanocrystals in SiO2 films is carried out by precipitation from a supersaturated solid solution of Ge in SiO2 made by Ge ion implantation. The films exhibit strong room-temperature visible photoluminescence. The measured photoluminescence peak energy and lifetimes show poor correlations with nanocrystal size compared to calculations involving radiative recombination of quantum-confined excitons in Ge quantum dots. In addition, the photoluminescence spectra and lifetime measurements show only a weak temperature dependence. These observations strongly suggest that the observed visible luminescence in our samples is not due to the radiative recombination of quantum-confined excitons in Ge nanocrystals. Instead, observations of similar luminescence in Xe+ -implanted samples and reversible PL quenching by hydrogen or deuterium suggest that radiative defect centers in the SiO2 matrix are responsible for the observed luminescence.
201 citations