Ion Implantation In Silica Research Articles

Quantum-dot composite silicate glasses obtained by ion implantation

Ion implantation is a useful technique to obtain composite materials such as nanocluster-containing silicate glasses. Depending on the choice of the pair `implanted atom–dielectric host', ion implantation of metals in glass gives rise to the formation of new compounds and/or metallic nanoparticles. In spite of the great interest, processes governing the chemical and physical interaction between the implanted atoms and the atoms in the host matrix are not completely understood. In this paper, metal, alloy and binary compound nanocluster formation is studied after ion implantation in silica and soda-lime glass. Particular emphasis is given to the comparison among different existing approaches to the understanding of the chemical interactions in these systems. As the physical properties of these composites depend on the cluster structure, composition and size, it is important to set procedures for modifying these characteristics. Recent results indicate that thermal treatments in controlled atmosphere of gold + copper double-implanted silica favor the formation of either alloy nanoclusters or copper compounds, depending on the annealing atmosphere.

Excimer laser annealing of glasses containing implanted metal nanoparticles

Silver and copper nanoparticles have been synthesized by ion implantation in silica and soda-lime silicate glass at 60 keV to a dose of 4×1016 ion/cm2 and at 50 keV to a dose of 8×1016 ion/cm2, respectively. The glasses were annealed using pulses of a high-power KrF excimer laser (248 nm) in ambient atmosphere. This employed a single (25 ns) pulse fluence of 0.25 J/cm2 for Ag-implanted samples or of 0.21 J/cm2 for Cu-implanted ones. Several pulses from 1 to 250 of the same energy density at a frequency of 1 Hz were accumulated in the same area on the surface. The formation and modification of metal nanoparticle was assessed via optical reflectance, combined with Rutherford backscattering analysis. Generally, changes induced by laser pulses suggest there are both reductions of the nanoparticles and some longer-range diffusion of metal atoms into the glass. However, before the total dissolution of metal nanoparticles is accrued, the substrate temperature, increasing during many-pulse treatments, initiates the regrowth of new metal nanoparticles that leads to a rise of the reflectance. These results are discussed on the basis of a surface substrate melting. This work is part of an attempt to gain control over the size and depth distribution of such metal nanoparticles.

Pd ion implantation in silica and alumina: chemical and physical interactions

Silica glass and polycrystalline alumina slides were implanted with palladium ions. Irradiations at 47 and 2 keV energies have been performed on silica samples, at 2 keV energy on alumina. Different fluences have been used in the 10 16 ion cm −2 range. Samples have been characterized by X-ray and ultraviolet photoelectron spectroscopies (UPS), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS) and optical absorption spectroscopy. In all samples, metallic palladium is present in the form of clusters whose diameter depends on the local dopant concentration. Moreover, palladium silicide compounds have been observed in the 5 × 10 16 Pd + cm −2 implanted silica sample. The valence band of these composites has been measured.

Mutually reactive elements in a glass host matrix: Ag and S ion implantation in silica

Ag, S, Ag + S, and S + Ag single and double ion implantations in silica glass were performed at room temperature. The implantation energies were chosen in order to get a projected range of 40 nm. The fluences were 2 × 1016 S+ cm−2 and 5 × 1016 Ag+ cm−2. Silver interacts weakly with the host silica matrix and forms essentially metallic clusters; this weak interaction between Ag and SiO2 induces formation of silver silicate rather than silver oxide. Double ion implantations of silver and sulfur lead to chemical interaction between the two species that is critically influenced by the implantation sequence. In particular, in the Ag + S sample silver and sulfur atoms react to form crystalline core (Ag)–shell (Ag2S) nanoclusters.

Composite materials obtained by ion irradiation: Mn implantation in silica glass

Ion implantation in silica is a useful way to generate unusual properties in glasses. To use ion implantation as a synthesis technique, it is necessary to understand the dynamics of the process. Silica glass samples, implanted with Mn at 38 keV energy and fluences of 1 × 1016, 5 × 1016 and 10 × 1016 ions cm–2 were investigated mainly by X-ray photoelectron (XPS), X-ray-excited Auger electron (XE-AES) and UV-photoelectron (UPS) spectroscopies. Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS) measurements, optical absorption and electron paramagnetic resonance (EPR) investigations were also performed. Mn silicate is present in all samples, while in the 5 × 1016 and 10 × 1016 samples Mn silicide compounds form in the most damaged region. These findings give further support to the two-step model as a simple method to predict the final compounds resulting from ion irradiation of a solid matrix.

Formation and optical characterization of multi-component Ag−Sb nanometer dimension colloids formed by sequential ion implantation in silica

The optical properties of nanometer dimension metal colloids formed by the sequential implantation of Ag then Sb in silica are characterized as a function of the relative concentrations of Ag and Sb implanted. The doses used were in ratios, Ag to Sb, of 9:3, 6:6 and 3:9. Energy of implantation was 305 keV for the Ag and 320 keV for the Sb. Nominal total doses as determined by current integration for the three samples were 12 × 10 16 (Ag + Sb) ions/cm 2 Single element colloids were also made by implantation using the same nominal doses as the sequentially implanted samples. Sequential in plantation of Ag and Sb leads to the formation of multi-component metal nanoclusters. Changes in the composition of the colloids from sequential implantation result in significantly different optical responses for these Samples compared to the single element implanted samples. The optical responses are consistent with results expected from effective medium theory.

Optical properties of gold nanocluster composites formed by deep ion implantation in silica

Planar layers of Au clusters with diameters between 5 and 30 nm were synthesized by implanting 2.75-MeV Au+ ions in fused silica. The metal-glass composite layer was 0.85 μm below the surface and had a width of 0.5 μm. Thermal annealing enhanced the optical absorption of the annealed samples near 2.4 eV. The third-order nonlinear optical response time is ≤35 ps; the magnitude of the effective nonlinear susceptibility is 200 times that of similar clusters embedded in ruby-gold melt glass.

イオンビームによるガラス基板へのリン珪酸ガラス層の形成

PSG layers were prepared by P+ ion implantation in silica, Na2O-SiO2, and Na2O-CaO-SiO2 glasses. The chemical state of the implanted P was evaluated by X-Ray photoelectron spectroscopy. In the silica glass, a part of the implanted P reacts with O. The remaining P are, however, oxidized by subsequent O+ implantation. Enhancement of the Na-gettering effect by the PSG layer in the additionally implanted O+ is observed by secondary ion mass spectrometry. In Na2O-SiO2 and NaO2-Ca0-SiO2 glasses, the oxidation of P depends on the glass composition and dose of P+ ions. In Na2O-SiO2 glasses, the number of oxidized P increased with an increase in the molecular ratio of Na2O/SiO2. Substitution of CaO for Na2O or SiO2 suppresses oxidization of the implanted P compared with the Na2O-SiO2 glass. The dependence of the oxidization of implanted P on the glass composition is discussed from the standpoint of surface-alkali depletion by ion implantation.

Luminescence during ion implantation of silica

During ion implantation of amorphous silica radiation damage is caused both by the nuclear collision loss term (d E/d x) nucl and to a lesser extent by the ionisation term (d E/d x) electronic. Our results clearly demonstrate that the relative contribution of the two terms influences the dependence of the luminescence intensity with ion energy and also the temperature variations. Under purely ionising conditions the activation energy of the temperature dependence is (p+0.085 ± 0.005) eV. The addition of a (d E/d x) n term alters the activation energy, and for low energy heavy ions (e.g. A + at 180 keV) the activation energy changes sign to values as high as (−0.06 ± 0.01) eV. In the ion energy dependence measurements we explain the form of the curve by including ionisation annealing of the metastable defects. Spectral measurements show features which can be interpreted as further evidence that the damage mechanism in silica involves exciton transitions.