G. W. Arnold

Aggregation and migration of ion-implanted silver in lithia-alumina-silica glass

The near‐surface nucleation and crystallization behavior of Ag+ ion‐implanted lithia‐alumina‐silica glasses has been studied. For room‐temperature Ag implants, crystallization of the glass ceramic phase was prevented by dissolution of Ag precipitates and migration of Ag atoms at temperatures below that necessary for formation of the glass ceramic phase. Crystallization was demonstrated after low‐temperature or low‐dose‐rate implantations. Optical spectroscopy was used to monitor the size of colloidal Ag particles and to detect the presence of the crystalline phase. Rutherford backscattering spectroscopy (RBS) was used to obtain the depth distribution of Ag atoms in the glass and thus monitor Ag migration. For samples implanted at room temperature and at relatively high dose rates (∼1 μA/cm2), aggregation of the Ag atoms into colloids occurred during implantation and also during subsequent annealing to temperatures ?350 °C. The RBS spectra indicate some migration of the Ag to the surface at these temperatu...

Near-surface nucleation and crystallization of an ion-implanted lithia- alumina-silica glass

Surface crystallization of a Au+‐ion‐implanted lithia‐alumina‐silica glass has been realized. Annealing of a glass sample implanted with 285‐keV Au+ ions at 550 °C results in the growth of colloidal Au particles of 18–35‐A radius. The Au particles constitute sites for the precipitation of lithium metasilicate crystals at 550 °C. Further annealing at 750 °C allows the growth of quartz and β‐spodumene crystals. The crystallized surface obtained after the high‐temperature anneal was characterized by a Knoop microhardness number of 626, which is of the order of that obtained for commerical volume‐crystallized glass‐ceramics of similar composition.

Peculiarities and application perspectives of metal-ion implants in glasses

Abstract Ion implantation in insulators causes modifications in the refractive index as a result of radiation damage, phase separation, or compound formation. As a consequence, light waveguides may be formed with interesting applications in the field of optoelectronics. recently implantation of metals ions (e.g. silver, copper, gold, lead, etc.) showed the possibility of small radii colloidal particles formation in a thin surface layer of the glass substrate. These particles exhibit an electron plasmon resonance which depends on the optical constants of the implanted metal and on the refractive index of the glass host. The non-linear optical properties of such colloids, in particular the enhancement of optical Kerr susceptibility, suggest that the ion implantation technique may play an important role for the production of all-optical switching devices. In this paper an analysis of the state-of-the-art of the research in this field will be presented in the framework of ion implantation in glass physics and chemistry.

Interaction of high‐power laser light with silver nanocluster composite glasses

The size and size distribution of silver nanoclusters embedded in soda‐lime glasses (formed by ion irradiation of Ag+–Na+ ion‐exchanged waveguides) has been modified by high‐power laser irradiation. Optical transmittance in the visible range is found to increase above the energy threshold E*=0.3±0.1 J/cm2 for λ=532 nm and E*=5±1 J/cm2 for λ=1064 nm for pulse lengths of about 10 ns. Cluster size reduction has been observed. Small radii silver nanoclusters are also formed after laser irradiation of ion‐exchanged waveguides. The optical response of the composites has been determined by optical absorption spectroscopy. Transmission electron microscopy, x‐ray photoelectron and Auger electron spectroscopies, and Rutherford backscattering spectrometry have been used to characterize the composites.

Irradiation-induced Ag-colloid formation in ion-exchanged soda-lime glass

Abstract Ion-exchanged glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1–20% AgNO3 in NaNO3, at temperatures varying from 320 to 350°C, and processing times of the order of a few minutes. Irradiations of exchanged samples were subsequently performed by using H+m, He+, N+ ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 × 1015 and 2 × 1017 ions/cm2. Most of the samples were treated at current densities lower than 2 μA/cm2, in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1–10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RBS), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.

Chemical aspects in copper‐implanted fused silica and soda‐lime glasses

Fused silica and soda‐lime glasses were implanted with copper, copper+nitrogen and copper+argon. Samples were characterized primarily by x‐ray photoelectron spectroscopy and x‐ray‐excited Auger electron spectroscopy. Measurements of optical absorption, transmission electron microscopy, secondary‐ion mass spectrometry, and Rutherford backscattering spectrometry were also carried out. Copper nanocluster formation and their size have been found to depend on the reactivity of the host vitreous matrix as well as on the implanted metal concentration. In the copper+nitrogen‐implanted fused silica a chemical interaction between copper and nitrogen together with the dissolution of the metallic nanoclusters has been observed. In the copper+nitrogen‐implanted soda‐lime glass interactions between substrate and nitrogen occur without the dissolution of copper precipitates. The dissolution of copper clusters is induced in the soda‐lime glass when implantation with argon (which does not chemically react with the host gl...

Formation of nonlinear optical waveguides by using ion-exchange and implantation techniques

Abstract Composite materials consisting of metal nanoclusters embedded in glass matrices have been obtained by the combined use of ion-exchange and ion implantation processes, with possible application in the design of nonlinear all-optical switching devices. Optical waveguides containing either silver or copper clusters have been fabricated. Optical absorption and electron microscopy have been performed to detect the presence of metal clusters. Preliminary measurements have been also performed of the optical nonlinear response on both silver- and copper-containing glasses.

Colloid formation in copper-implanted fused silica and silicate glasses

Abstract Copper implantations (90 keV, 5 × 10 16 ions/cm 2 ) were made into fused silica, borosilicate glasses and soda-lime glass. The copper distribution has been found to vary according to glass type. The optical absorption band characteristic of the implanted metal optical properties was observed only for copper-implanted fused silica. The absorption for all the other samples was either not observable or was negligibly small, however very small metallic particles are present also in the soda-lime glass. A subsequent nitrogen implantation (100 keV, 1.5 × 10 17 ions/cm 2 ) completely eliminated the copper-colloid induced absorption in the copper-implanted fused silica, while it facilitated the formation of copper-colloids into the soda-lime glass.

Defect diffusion in ion implanted glasses

Abstract Ion implantation in glasses produces structure modifications at depths greater than those of the implanted ion range. Such a result is evidenced by means of leaching experiments, alkali element depletion, distribution of gaseous implanted species, etching rate as function of depth. A systematic study with the aim to evidence a threshold in the nuclear deposited energy for defect diffusion is presented. Fourier transform infrared spectroscopy measurements confirm the glass modifications at extended depths.

Zinc-implantation-disordered (InGa)As/GaAs strained-layer superlattice diodes

We have examined the properties of (InGa)As/GaAs strained‐layer superlattices (SLSs) that have been disordered by implantation of 5×1015/cm2, 250 keV 64Zn+ followed by controlled atmosphere annealing at 680 °C for 30 min. Ion channeling techniques indicate that the Zn‐disordered regions of the SLS contain extensive crystalline damage after annealing. Simulations of the disordering process using an analytic ion range code predict that the electrical junction resulting from the implantation process is located outside the disordered region of the SLS in both the vertical and the lateral directions. Junction electroluminescence intensity for given drive current densities from the Zn‐disordered SLS devices is comparable to that from reference Be‐implantation‐doped (SLS retained) devices and greatly exceeds that from heavily dislocated grown‐junction mesa diodes in the homogeneous alloy of the average SLS composition; this result is consistent with the results of the simulations. This study demonstrates that im...