Ionizing radiation is used to structure the surfaces of transparent polymers like poly-(methyl-methacrylate) and related materials. Areas with an index increase up to 1 percent sufficient for waveguiding are obtained. The method of waveguide fabrication in polymers by ionizing radiation is described in detail. The compaction of the irradiated areas accompanied by the index increase is used to make diffractive structures. By a special embossing technique devices with directly coupled fibers are obtained. The chemical processes in the material generated by the irradiation procedure are measured by spectroscopic methods, the optical properties of the components are reported.

Swift heavy ions (SHI) have velocities around or above the velocity of K-shell electrons, which corresponds to energies ranging from a few MeV/amu to about 100 MeV/amu. They interact with matter mainly by inelastic collision processes leading to ionization of the target atoms and excitations of the target electrons: Nearly all of the SHI energy is lost in the electronic stopping power (dE/dx)_e range. Most of the work concerning SHI effects in materials concern biological matter and materials insensitive to radiation damage processes such as metals or metallic oxides. On the contrary, few studies have been published concerning high (dE/dx)_e effects in radiolysis sensitive materials such as polymers. This contribution deals with the chemical effects induced by SHI in polymers, but also other fluorinated polymers, polyethylene, polystyrene. Several kind of defects are created. The influence of irradiation parameters is presented. Different evolutions when (dE/dx)_e increases is observed. Some defects are specific of SHI and thus appear only at high (dE/dx)_e. Some see the yield of creation increased on high (dX/dx)_e while others are so easily formed that increasing the (dE/dx)_e does not affect their yield.

A series of polystyrene (PS) and polymethylmethacrylate (PMMA) materials were implanted with 50 keV nitrogen ions to a dose in the range of 1-8 X 10¹⁵ to determine optical losses in the visible range. The transmission results indicate a minimum at about 350 nm for both the PS and PMMA materials, in agreement with previous experiments. This minimum changes in amplitude and shifts to longer wavelengths with increasing dose. A similar minimum is observed in 1000A sputter deposited C films on PS and PMMA substrates. However, the density of scattering centers responsible for the minimum, is higher in the implanted materials than in the carbon sputtered materials. The electrical and to some extent, the optical, properties of ion implanted polymers are unstable. By truncating the microstructure, toward the mean range of the implant ion, the electrical resistivity can be stabilized to about a 3 percent change per year. To further reduce this stability problem, we ion beam mixed 200-500A metallic films on polytetrafloroethlene. The resulting polymer/metallic composite has a highly conductive layer slightly below the surface and is bonded securely to the polymer substrate. Ion beam analysis result suggest that by this method we can produce metallic layers under the surface of the polymer.

Our work consists in the study of ion implantation effects on the linear and nonlinear optical properties of polymer thin films. This project started with developing god quality planar waveguides based on a well-known photoconductor polymer, the polyvinylcabazole. This polymer, which as no nonlinear properties, is deposited by spin coating on a BK7 substrate. A diffraction grating etched on the substrate surface, will act as an input coupler for the waveguide. We present here our latest results concerning the study of these polymer waveguides exposed to energetic ion beam. We are using the grating coupler method to characterize the linear and nonlinear optical properties of these waveguides before and after ion implantation. Due to the conjugated chains created by the implantation, we expect (chi) ⁽³) type nonlinear properties and more specifically electronic nonlinear refractive index. Concerning the structural modifications, the implanted polymer films are studied by IR and UV/visible spectroscopy. We will lay emphasis on the new structures created as well as on the important destruction caused by implantation.

Glazing, of the type used for the coating of electrical insulator, has been irradiated by means of 3 keV H, He, N and Ar ions with fluences from 2 X 10^-3C/cm² to 4 X 10^-2c/cm². Some exposures were performed under oxygen partial pressure. After treatment, the samples were stored in different environments for times varying from 3 to 1080 minutes. The samples were characterized by means of contact angel hysteresis measurements and x-ray photoelectron spectroscopy (XPS). Irradiation with hydrogen ions produced a more hydrophobic surface and aging has little effect on the wettability. The other conditions of irradiation produced a more hydrophilic surface immediately after treatment. However, after an aging of approximately 150 hours, the samples became hydrophobic. This transition from a hydrophilic to a hydrophobic surface was not found to depend strongly upon the irradiation or storage conditions. Characterization by means of angel- resolved XPS has shown a noticeable change in the composition of the glazing surface. In general, the irradiation removes a large portion of oxygen present in the pre-existing carbonaceous layer on the surface of the glaze. Also, according to a simple model describe din this article, the ion beam irradiation seems to enhance the concentration of the carbonaceous layer in islands on the glazing surface. The effect of aging seems to be due to a re-spreading of these islands to form a more homogeneous surface layer rich in carbon which leads to an increase in the hydrophobicity of the surface.

We show that ion beam assisted deposition (IBAD) can result in films of metal or semiconductor nanoclusters in dielectric matrices with nonlinear optical (NLO) or photoluminescence (PL) properties. Gold nanocluster thin films consisting of metal clusters 5-30 nm in size embedded in a Nb₂O₅ or a SiO₂ oxide matrix were deposited by ion beam assisted deposition by co-evaporation of Au and Nb or Si with O₂+ ion bombardment. Semiconductor nanocluster films have been prepared by IBAD as well. Silicon-rich silica films were deposited by coevaporation of silica and silicon with and without simultaneous ion bombardment. PL attributable to defects in SiO₂ was observed at about 550 nm. After annealing, the PL peak shifts to 750 nm and increases in intensity, indicating the formation of Si nanoclusters. Transmission electron microscopy (TEM) images of annealed IBAD films show a dense distribution of mostly spherically shaped crystalline Si nanoclusters, about 1-4 nm in diameter, in a featureless amorphous SiO₂ matrix. TEM images of films prepared without ion assist showed many less crystalline Si clusters, that were more irregularly shaped, within 0.1 micrometers amorphous silica grains. Passivation of the films with hydrogen removes the defect PL peak and enhances the peak due to nanoclusters. We have also prepared Ge nanoclusters in silica films with and without IBAD.

The range of microstructures and properties of sapphire that are produced by ion implantation are discussed with respect to the implantation parameters of ion species, fluence, irradiation temperature and the orientation of the ion beam relative to crystallographic axes. The microstructure of implanted sapphire may be crystalline with varying concentrations of defects or it may be 'amorphous', perhaps with short-range order. At moderate to high fluences, implanted metallic ions often coalesce into 'pure' metallic colloids and gas ions form bubbles. Many of the implanted microstructural features have been identified from studies using transmission electron microscopy, optical spectroscopy, Moessbauer spectroscopy, and Rutherford backscattering-channeling. The chemical, mechanical, and physical properties reflect the microstructures.

Silicon ions were implanted into fused silica substrates at doses of 1 by 10²¹, 2 by 10²¹, 5 by 10²¹, and 1 by 10²² ions/cm³. The implanted substrates were subsequently annealed at 1100 degrees C for one hour in a reducing atmosphere. Optical absorption spectra recorded after the annealing treatment showed absorption onsets at 316, 373, 434 and 493 nm for substrates implanted with 1 by 10²¹, 2 by 10²¹, 5 by 10²¹, and 1 by 10²² ions/cm³ respectively. Static photoluminescence (PL) measurements indicated red emission between 720 and 770 nm with a slightly increasing red shift with ion dose. Time resolved PL at room temperature revealed slow and fast lifetimes which increased with decreasing temperature. TEM studies showed that the particles size increased with increasing ion dose with typical particle sizes ranging between 2 and 5 nm indicating quantum confinement of the exciton which can account for the blue shift in the absorption edge with decreasing ion dose. However, the maxima in the PL spectra for all ion doses are relatively independent of the ion dose and are strongly Stokes shifted from the absorption spectra suggesting that radiative recombination occurs from a common luminescent center, possibly a surface or interfacial state in the SiO_x layer surrounding the nanocrystal.

Composite silicate glasses containing nanometer-sized metal clusters can be prepared by using ion beams. In particular, metal species can be directly implanted into the glass matrix. Alteratively, low-mass ion beams ca be effectively used for promoting cluster aggregation in surface layers of glass previously doped with metal. Some recent results are presented on these ion-beam-based methodologies for obtaining metal quantum-dot composite glasses, with particular attention to sliver and copper-doped systems.

We report linear and nonlinear optical properties of planar waveguides produced by implantation of MeV Ag ions into LiBnO₃. The linear optical properties include spectrum of propagation modes and optical extinction spectrum. The nonlinear properties include optical spectrum of nonlinear refractive index and nonlinear absorption. Light guiding in the implanted crystal is associated with the modification of the linear refractive index. The modification is a result of two concurrent processes such as crystal is damage in the nuclear stopping region producing a low index optical barrier between the top light guiding layer and the bulk crystal and the diffusion of the implanted ions into the implanted ions into the top layer causing its index increase. Relatively high nonlinear refractive index is a result of enhancement of intrinsic third order nonlinearity of the implant by the mechanism of surface plasmon resonance. The intrinsic nonlinearity is associated primarily with intraband and interband electron transitions. The spectrum of the nonlinear index correlates with the spectrum of optical extinction featuring prominent peak due to surface plasmon resonance. Possible applications of the waveguides include ultrafast photonic switches and modulators.

A novel technique for quantum well intermixing is demonstrated which has proven to be a reliable means for obtaining post-growth shifts in the band edge of a wide range of III-V material systems. The techniques relies upon the generation of point defects via plasma induced damage during the deposition of sputtered silica, and provides a simple and reliable process for the fabrication of both wavelength tuned lasers and monolithically integrated devices. Wavelength tuned board area oxide stripe lasers are demonstrated in InGaAs-InAlGaAs, InGaAs-InGaAsP, and GaInP- AlInP quantum well systems, and it is shown that low absorption losses are obtained after intermixing. Oxide stripe lasers with integrated slab waveguides have also enabled the production of a narrow single lobed far field pattern in both InGaAs-InAlGaAs, and GaInP-AlGaInP devices. Extended cavity ridge waveguide lasers operating at 1.5 micrometers are demonstrated with low loss waveguides, and it is shown that this loss is limited only by free carrier absorption in the waveguide cladding layers. In addition, the operation of intermixed multi-mode interference coupler lasers is demonstrated, where four GaAs-AlGaAs laser amplifiers are monolithically integrated to produce high output powers of 180 mW in a single fundamental mode. The results illustrate that the technique can routinely be used to fabricate low los optical interconnects and offers a very promising route toward photonic integration.

A technique, base don quantum well (QW) intermixing, has been developed for the post growth, spatially selective tuning of the QW bandgap in a semiconductor laser structure. High energy ion implantation is used to create a large number of vacancies and interstitials in the device. During high temperature processing, these defects enhance the intermixing of the QW and the barrier materials while being annealed out, producing a blue shift of the QW bandgap. Increases in bandgap energy of greater than 10 nm at 1.55 micrometers in InGaAs/InGaAsP/InP structures can be achieved. Absorption spectroscopy in the waveguide geometry is used to quantify the losses in the structure. Using a simple masking scheme to spatially modify the defect concentration, different regions of a wafer can be blue shifted by different amounts. This allows the integration of many different devices such as lasers, detectors, modulators, amplifiers and waveguides on a single wafer using only a single, post-growth processing step. The performance of both passive and active devices produced using this technique will be described, as well as the practicality of this technique in the production of photonic integrated circuits.

A monolithic optoelectronic chip containing multiple emission wavelength laser diodes has been developed. The semiconductor quantum well lasers have Fabry-Perot cavities of 500 micrometers in length. Electrical insulation between individual integrated devices has been achieved by wet etching the top contact layer and by a lift-off of the surface metal contact between the different lasers. The electroluminescence peak emission spectra of the integrated laser diodes has been shifted over a 25 nm range and 74 nm for discrete devices. Blueshifting of the emission wavelength has been achieved by quantum well intermixing using an industrial low energy ion implanter to generate point defects and a rapid thermal annealer to promote interdiffusion of the barrier and quantum well atoms during the recrystallization anneal. Phosphorus ions were implanted with an energy of 360 keV to precisely defined regions of the heterostructure with SiO₂ serving as a masking material. Thus reference and intermixed regions were integrated on a single component. Integrated and discrete laser diodes have been assessed in terms of threshold currents and emission wavelengths.

A comparison has been made of the shifts induced in the photoluminescence (PL) emission wavelength of a GaAs/AlGaAs multiple quantum well (QW) structure following irradiation with H, He and As ions. Ions energies and fluences were chosen to produce matching numbers and distributions of lattice atom displacements across the structure. Samples were then annealed at 900 degrees C for 30s to intermix the QWs and low temperature photoluminescence as used to measure the shifts in the QW bandgap energies. At common concentration of atomic displacements, the PL blueshift increased with the mass of the implanted ion. For these anneal parameters, saturation of the blueshift from the narrowest QW was observed in all three irradiation at an average vacancy production concentration of approximately 10²² cm^-3. No significant difference in PL shifts was found when the irradiations were performed at 200 degrees C sample temperature.

In this paper we present two different applications of ion implantation in chalcogenide glasses: rare earth doping and channel waveguide fabrication. The luminescence of a neodymium-implanted arsenic tri-sulfide waveguide at 1083 nm is reported. The most efficient pump wavelength is determined to be 818 nm. The dopant distribution following ion implantation is predicted by molecular dynamic simulation and measured by Rutherford Backscattering Spectrometry. This observation of luminescence from rare- earth ion implantation into chalcogenide glass suggest that this technique can be useful for rare-earth doped devices. A study of neodymium luminescence peak power as a function of dopant concentration is reported. The second application of ion implantation is in the fabrication of channel waveguides by helium implantation.

Los Alamos National Laboratory is actively researching a surface modification technique called plasma immersion ion processing (PIIP). PIIP is the latest innovation of the plasma source ion implantation (PSII) approach to surface modification. Like PSII, PIIP allows the modification of large areas and non-planar surface geometries, however PIIP is primarily a coating deposition technology rather than solely an ion implantation technology. PIIP utilizes a pulsed-bias on a target to extract ions out of plasma for ion implantation and coating deposition. Plasmas can be made by capacitive or inductive radio frequency sources or by initiating a glow discharge during each pulse of high voltage. Plasmas of hydrocarbon gases have been used to deposit adherent diamond-like carbon (DLC) coating son a variety of ferrous and non-ferrous materials. Instead of sputter depositing interlayers to improve the adhesion of DLC, PIIP uses ion implantation to create a graded interface between the metallic substrate and the DLC coating. Demonstrating the scaleability of PIIP, a 3 m² area has been simultaneously coated with an adherent DLC coating approximately 7 micrometers thick. Plasmas of diborane and acetylene mixtures are being used to develop deposition processes for boron-carbide coatings. Through the use of organometallics and inorganic gases, other coatings are possible. The PIIP deposition conditions, composition and tribological properties of DLC and boron-carbide coatings will be highlighted.

The University of Montreal recently inaugurated a new 1.7 MV Tandem accelerator for materials research. It is being used to study a wide range of topics involving optical, electronic, opto-electronic, and magnetic materials. Current research includes: threshold dose for secondary damage in Si, gettering of impurities in Si by nano-cavities, ion beam mixing of metallic multilayers probed by giant magnetoresistance, tracks and deformations induced by multi- MeV ion beams, and high-resolution radial distribution function of pure amorphous silicon. A selection of recent results is discussed.

The effects of single ion impacts on the surfaces of films of Au, Ag, In and Pb have been studied using in-situ transmission electron microscopy. On all these materials, individual ion impacts produce surface craters, in some cases, with associated expelled material. The cratering efficiency scales with the density of the irradiated metal. For very thin Au foils, in some cases individual ions are seen to punch small holes completely through the foil. Continued irradiation result in a thickening of the foil. The process giving rise to crater and hole formation and other changes observed in the thin foils has been found to be due to pulsed localized flow - i.e. melting and flow due to the thermal spikes arising form individual ion impacts. Experiments carried out on thin films of sliver sandwiched between SiO₂ layers have indicated that pulsed localized flow also occurs in this system and contributes to the formation of Ag nanoclusters in SiO₂ - a system of interest for its non-linear optical properties. Calculation indicates that, when ion-induced, collision cascades occur near surfaces with energy densities sufficient to cause melting, craters are formed. Crater formation occurs as a result of the explosive outflow of material from the hot molten core of the cascade. Processes occurring in the sandwiched layer are less well understood.

A novel technique, was developed to implant gaseous ions into the surface of metallic objects with arbitrary geometry. A system presenting a pulsed ECR plasma and a constant voltage of the target has the advantage of monoenergetic implantation. Depth distribution and chemical interactions were investigated by AES and XPS. Surface microstructure and friction forces on the nanometric scales were evaluated by AFM. We found that the depth of implantation can be controlled by the sample position relative to the extraction grid, which may have benefits for certain applications. The evolution of the implantation indicates that, at room temperature, the chemical reactions involved lead to sub-stoichiometricor composite products. In the nitriding case, an increase in microroughness and a reduction of local friction forces on the nanometric scale were found.

High melting point, low atomic numbers and resistance to thermal fatigue and erosion are the desirable attributes of materials for fusion containment vessels, limiters and other components. However, such materials are subjected to hydrogen ion bombardment from a circulating plasma. this interaction results in the formation and adsorption of various molecular complexes on material surfaces. Their release as an impurity can poison the plasma and lower its temperature, as well as cause surface damage. We have undertaken the characterization of three such surfaces, and the results are reported.

Modern short pulse lasers are efficient tools for production of high levels of electronic excitation in solids under irradiation, a state which mimics that of the same materials after the passage of any particle which deposits its energy under the form of electronic excitation. Because they can also be used in a number of optical experiments of charge carriers and defect detection, they offer the unique opportunity of unraveling the ultrafast kinetic aspects of atomic processes induced by the electronic excitation, whose final state is the only aspect accessible in the case of other irradiations. After mentioning a few orders of magnitudes concerning the energy deposition, we will show some examples of recent experiments concerning the mechanisms of irradiation defect creation in insulators. The perspectives opened by recent developments of light sources in a wide range of wavelengths will be finally presented.

Samples of four modern steels were implanted with 120 keV N₂⁺ ions at doses ranging from 5 X 10¹⁵ to 1.2 X 10¹⁷ ions/cm² at room temperature. The sample surfaces were studied for their tribological properties. The Knoop microhardnesses increased by 9 percent to 30 percent after ion implantation. A heat treatment study from 200 degrees C to 600 degrees C on AerMet 100 and Sverker 21 following implantation with 8 X 10¹⁶ ions/cm² of nitrogen comparing implanted to unimplanted samples shows that the hardness reduction arising for the heat treatment was lower for the implanted samples. The projected ranges for the implanted specimens were obtained using the TRIM program. The microhardness of the implanted layers alone was calculated by the Hoensson-Hogmark model. The residual stress of the Orvar Supreme surface after 60 keV nitrogen ion implantation at a dose of 8 X 10¹⁶ ions/cm² was also measured by x-ray diffraction. The friction and wear test was obtained using an Optimol SRV friction and wear tester. After nitrogen implantation and heat treatment, samples were depth profiled by AES and XPS.

The wetting property of polymers is very important in different applications such as optics, biomaterials, textiles, aerospace, and thin film adhesion. Hence the strong interest in developing new technology for modifying this property at will. Low energy ion beams can induce this modification in the first surface atomic layers. Nitrogen ions of 500 eV/at. and argon ions of 3 keV/at. under partial pressure of oxygen were used to bombard the surface of polycarbonate samples to a fluence of 5 X 10¹⁶ at/cm² and 2.1 X 10¹⁷ at./cm², respectively. After implantation, the samples were stored in two different environments over controlled intervals of time. Characterization of samples was performed by means of XPS, ERD ExB and RBS. The result show an increase of the oxygen concentration near the surface for all implanted samples. Also, desorption of hydrogen was observed after implantation of argon under a partial pressure of oxygen. These results confirm the formation of new functional groups such as C-OH for all treatments. These groups are known to enhance the wettability of the polycarbonate surface.

The technology of obtaining the interference coatings for the nonlinear crystals has some peculiarities depending on the specific properties of these crystals. Temperature, pressure of reactive gas and energy of charged particles do not affect principally the optical properties of the nonlinear crystal. In this paper the various aspects of thin dielectric films for crystals are presented. There are calculations of the optimum structure of the optical coating for specific spectral region, obtaining the required parameters of the films having the optical properties that would not impair the own properties of the crystal parameters of the films having the optical properties. As a rule, the coatings of these crystals that could be coated without heating in a vacuum chamber. As the result of this work the various types of the interference coatings have been obtained. There are the AR coating at a single wavelength in the spectral range of 0.24...1.5 micrometers , the broad-band AR coatings, the AR coating with two AR spectral regions simultaneously.

Some aspects of obtaining high reflective (HR) dielectric mirrors with high damage threshold (LDT) for high-power solid-state near IR region (NIR) lasers are considered. Optical properties of these mirrors were investigated as properties of each alternate layer evaporated with high- index (H) or low-index (L) materials as multilayer system that depends on mirror construction, parameters of evaporation, ion-beam influence, substrate materials and quality of substrate surface. Refractory oxides ZrO₂,HfO₂, Ta₂O₅, Al₂O₃ and SiO₂ were used as starting materials for evaporation. Ion-beam influence was estimated as changing of optical absorbance at a wavelength 1.064 micrometers by laser modulated photo-thermal radiometry. Besides the quality of various work-up substrate surface was controlled by this method also. It was noticed that substrates with different surface roughness had different absorption. It was noticed that band edge of absorption of pure substrate in UV region influenced on laser damage threshold of mirrors. Optical properties of evaporated mirrors were tested as the ability of strength for laser irradiation as cavity-mirrors of high power lasers. ZrO₂/SiO₂ mirrors had the most high laser strength. Estimated value of laser density was 3.6 GW/cm².

Ion implantation of semiconductors results in the introduction of vacancies, interstitials, antisites and complexes involving these defects. The donor to gallium vacancy and the free electron to gallium vacancy transitions occurs at 1.4745 and 1.4785 eV respectively in the photoluminescence (PL) spectrum of irradiated n-type gallium arsenide (GaAs) slightly doped with silicon, when the samples temperature is 4K. We have implanted 4 micrometers thick GaAs films grown on bulk GaAs with carbon, oxygen and arsenic ions in order to determine the V_Ga introduction rate using PL. The particle energy was chosen such that the stopping range covered 2 to 20 micrometers . The production rate is in agreement with Rutherford scattering theory, in which only primary knock out processes are considered when the stopping range is much greater than the epilayer thickness, but less than the theory when the particles are implanted in the epilayer. Since vacancies are created by both primary and secondary ion collisions and removed by recombinations, the data suggests that secondary ion collisions and recombinations are unimportant at high energies when the particles go right through the samples, or that their effects cancel out. At low energies, when implantation occurs, the combined data suggests that vacancies are removed through recombinations at a faster rate than they are produced by secondary ions collisions.