The linear and nonlinear optical properties of nanometer dimension metal colloids embedded in a dielectric depend explicitly on the electronic structure of the metal nanoclusters. The ability to control the electronic structure of the nanoclusters may make it possible to tailor the optical properties for enhanced performance. By sequential implantation of different metal ion species multi-component nanoclusters can be formed with significantly different optical properties than single element metal nanoclusters. We report the formation of multi-component Sb/Ag nanoclusters in silica by sequential implantation of Sb and Ag. Samples were implanted with relative ratios of Sb to Ag of 1:1 and 3:1. A second set of samples was made by single element implantations of Ag and Sb at the same energies and doses used to make the sequentially implanted samples. All samples were characterized using RBS and both linear and nonlinear optical measurements. The presence of both ions significantly modifies the optical properties of the composites compared to the single element nanocluster glass composites. In the sequentially implanted samples the optical density is lower, and the strong surface plasmon resonance absorption observed in the Ag implanted samples is not present. At the same time the nonlinear response of the these samples is larger than for the samples implanted with Sb alone, suggesting that the addition of Ag can increase the nonlinear response of the Sb particles formed. The results are consistent with the formation of multi-component Sb/Ag colloids.

Various silicate glasses (fused silica, soda-lime, Na- and K-borosilicates, lithia-alumina silicate, and Pyrex®) were implanted with 8 x 1015 285 keV Au/cm2. Colloid growth was monitored as a function of annealing and N implantation (2 x 1017 35 keV N/cm2). Annealing to 1040 °C for fused silica and to 600 °C for the other glasses resulted in Au aggregation and optical absorption. Radiation damage removal is associated with the fused silica annealing; the aggregation of Au at lower temperatures for the other glasses is expected because of the lower glass transition temperature. Phase-seption in the alkali-borosilicates may be important because of grain-boundary diffusion. N implantation did not significantly affect nanocluster growth.

Ion implantation has been used to form nanocrystals in the near surface of single crystal A12O3. The ion fluence was 5 x 1016 Y+/cm2, and the implant energies investigated were 100, 150, and 170 keV. The morphology of the implanted region was investigated using transmission electron microscopy, x-ray energy dispersive spectroscopy, Rutherford backscattering spectroscopy and ion channeling. The implantation causes the formation of an amorphous surface layer which contains spherical nanosized crystals with a diameter of ∼13 nm. The nanocrystals are randomly oriented and exhibit a face-centered cubic structure with a lattice pmeter of ∼4.1 A ± .02 A. Preliminary chemical analysis shows that these nanocrystals are rich in aluminum and yttrium and poor in oxygen relative to the amorphous matrix.

Silica platelets (Corning 7940) were implanted sequentially with N at 52 keV to different doses ranging from 0 to 1.2×l017 ions cm2 and then with Fe at 160 keV to a dose of 6×10 ions cm2. The optical absorption decreased with increasing N1 dose at photon energies ranging from 1.4 eV to 6.5 eV. The relative intensity, S(0°), of the ferromagnetic resonance absorption and its resonance field, H(0°), at θ = 0° were larger than S(90°) and H,(90°) at 0 = 90°, where Θ is the angle between the applied magnetic field and the normal to the implanted surface. The maximum values of S(0°) and S(90°) were observed near the N/Fe atomic ratio of 0.2. At the similar atomic ratio, the differential relative intensity, S(0°)- S(90°), and the differential resonance field, H,(0°)-H,(90°). associated with the degree of magnetic interaction between the produced compounds, also showed maxima. We conclude that sequential ion-implantation of N1 and Fe1 into silica causes a chemical interaction to produce iron nitrides.

Low loss channel waveguides have been formed in substrates of fused silica and silica-on-silicon by the implantation of 5 MeV Si, P and Ge ions. The silica-on-silicon substrates comprised an upper core layer which was doped with either 3 or 7% Ge. Annealing of the implanted silica-on-silicon waveguides has defined a narrow range of temperature (500 - 600°C) over which the loss coefficient, α, was at a minimum of 0.10 - 0.20 dB/cm at wavelengths of λ = 1300 and 1550 nm. For the fused silica substrates, a similar minimum loss ( 0.10 - 0.20 dB/cm) was measured at 1300 nm. However, at λ = 1550 nm the value of α was significantly increased because of an absorption edge in the fused silica (Suprasil-2) at -1500 nm. The results show that the optical loss characteristics of the waveguides were essentially independent of the ion species.

The implantation of Ag into MgO (100) single crystals, followed by thermal annealing at 1100°C, leads to dramatic changes in their optical properties. The changes in the optical properties are due to the presence of small Ag clusters which are formed in the annealed samples. The small Ag clusters are obtained by thermal annealing of the implanted MgO crystals between 600°C and 1100°C to investigate the changes in cluster sizes and to correlate with changes in their optical properties. Sample characterization is carried out using optical spectrophotometry to confirm the effective presence of Ag clusters and Rutherford Backscattering Spectrometry (RBS) to study the profile of Ag clusters.

The contributions of ionization energy losses and elastic collisions to radiation induced defect formation along the proton track were considered in quartz glasses irradiated by protons with different energies. It is shown that on a larger part of the proton track the color and luminescence center formation by means of recharging of the native defects is due to the ionization energy losses. Generation of structural defects like displaced atoms and their vacancies by elastic collisions with protons and recoil atoms dominates for proton energies < 5 MeV. At proton energies 10 MeV the color and luminescence center formation due to ionization energy losses prevails, and generation of the alumina-alkaline centers, causing an increase of the optical absorption at 550 nm and the thermoluminescence peak at 360 C and a band at 460 nm, occurs. At the proton energies Ep 10 MeV generation of the displaced atoms and their vacancies by elastic collisions dominates, leading to an increase of the E'-centers and to the destruction and transformation of the alumina-alkaline centers.

Metal nanocluster thin films (∼200 nm thickness) consisting of noble metal (Au) clusters (5-30 nm) in an active metal oxide (Nb2O5) matrix were deposited by evaporation or ion beam assisted deposition (IBAD). In some cases the films were given a post-deposition anneal. The microstructure of the films was examined by plan view and cross sectional transmission electron microscopy (TEM). The size of the metal nanoclusters was found to depend upon the temperature of the post-deposition anneal as well as the conditions of ion bombardment. Ion bombardment was found to stabilize smaller size particles. The linear optical properties of the films, as measured by VIS/UV spectroscopy, show particle size-dependent surface plasmon resonance effects. The nonlinear optical (NLO) properties of the nanoclusters in oxidized niobium were probed experimentally using degenerate four wave mixing (DFWM) and nonlinear transmission (NLT). The DFWM measurements yielded signals that showed strong evidence of saturation and give large values of χ(3)xxxxl. NLT measurements demonstrated that the nonlinear absorption coefficient and, hence, Imχ(3)xxxx was negative. Time resolved DFWM measurements exhibited dynamics that decayed on a several picosecond time scale. The magnitude and the picosecond dynamics of the NLO response were compared to those observed in gold nanoclusters formed by ion implantation in other media. The advantages of the IBAD method for fabricating third order NLO films include the ability to deposit films of arbitrary active region thicknesses and, more importantly, high cluster densities.

The optical, structural, and thermodynamic properties of materials can be changed by reducing their dimensions. We sequentially implanted In and As into fused silica windows in order to investigate the formation and properties of InAs nano-particles. The UV/VIS/NIR, FTIR in mid-IR, and far-IR spectroscopy were mainly used to study the change in electronic transitions and in vibrational modes (phonons) of the nanoparticle InAs. The phonons can be confined to the surface of nanoparticles and have frequencies falling between the transverse and longitudinal optical modes of the bulk material. Thermal annealing developed the formation of InAs quantum dots from as-implanted In+As system. At a certain annealing temperature, we observed a change in UV/VIS transmission spectra and IR reflectance spectra indicating the formation of InAs quantum dots. This is particularly evident from the absorption in the IR, and surface phonon bands are observed confirming the presence of quantum confined InAs.

GaAs nanocrystals have been formed by the sequential ion implantation method. The sequence of Ga and As ion implantation (i.e., Ga + As or As + Ga) is found to affect the size distributions of GaAs nanocrystals significantly. The nanocrystal sizes are much bigger in the samples with Ga implanted first than those with As implanted first. This phenomenon is explained by the different diffusion behaviors of Ga and As species. Different precipitate regions have been observed in the samples implanted with Ga first and then As. Optical absorption measurements show that Ga particles have already formed in the as-implanted stage.

Ion beam processing, including ion implantation and ion beam assisted deposition (IBAD), are established surface modification techniques which have been used successfully to synthesize materials for a wide variety of tribological applications. In spite of the flexibility and promise of the technique, ion beam processing has been considered too expensive for mass production applications. However, an emerging technology, Plasma Source Ion Implantation (PSII), has the potential of overcoming these limitations to become an economically viable tool for mass industrial applications. In PSII, targets are placed directly in a plasma and then pulsed-biased to produce a non-line-of-sight process for intricate target geometries without complicated fixturing. If the bias is a relatively high negative potential (20-100kV) ion implantation will result. At lower voltages (50-1200V), deposition occurs. Potential applications for PSII are in low-value-added products such as tools used in manufacturing, orthopedic devices, and the production of wear coatings for hard disk media. This paper will focus on the technology and materials science associated with PSII.

Ion implantation by intense beams of metal ions can be accomplished using the dense metal plasma formed in a vacuum arc discharge embodied either in a vacuum arc ion source or in a ‘metal plasma immersion’ configuration. In the former case high energy metal ion beams are formed and implantation is done in a more-or-less conventional way, and in the latter case the substrate is immersed in the plasma and repetitively pulse-biased so as to accelerate the ions at the high voltage plasma sheath formed at the substrate. A number of advances have been made in the last few years, both in plasma technology and in the surface modification procedures, that enhance the effectiveness and versatility of the methods, including for example: controlled increase of the ion charge states produced; operation in a dual metal-gaseous ion species mode; very large area beam formation; macroparticle filtering; and the development of processing regimes for optimizing adhesion, morphology and structure. These complementary ion processing techniques provide the plasma tools for doing ion surface modification over a very wide parameter regime, from ‘pure’ ion implantation at energies approaching the MeV level, through ion mixing at energies in the ∼1 to ∼100 keV range, to IBAD-like processing at energies from a few tens of eV to a few keV. Here we review the methods, describe a number of recent developments, and outline some of the surface modification applications to which the methods have been put.

The origin of residual stresses were studied in both crystalline metallic films and amorphous oxide films made by ion beam assisted deposition (IBAD). Monolithic films of AI2O3 were deposited during bombardment by Ne, Ar or Kr over a narrow range of energies, E, and a wide range of ion-to-atom arrival rate ratios, R and were characterized in terms of composition, thickness, density, crystallinity, microstructure and residual stress. The stress was a strong function of ion beam parameters and gas content and compares to the behavior of other amorphous compounds such as MoSix and WS12.2 With increasing normalized energy (eV/atom), residual stress in crystalline metallic films (Mo, W) increases in the tensile direction before reversing and becoming compressive at high normalized energy. The origin of the stress is most likely due to densification or interstitial generation. Residual stress in amorphous films (Al2O3, MoSix and WSi2.2) is initially tensile and monotonically decreases into the compressive region with increasing normalized energy. The amorphous films also incorporate substantially more gas than crystalline films and in the case of Al2O3 are characterized by a high density of voids. Stress due to gas pressure in existing voids explains neither the functional dependence on gas content nor the magnitude of the observed stress. A more likely explanation for the behavior of stress is gas incorporation into the matrix, where the amount of incorporated gas is controlled by trapping.

Titanium nitride films were produced by a newly developed photon and ion beam assisted deposition system (PHIBAD system). With an electron beam evaporator titanium was deposited on silicon substrates in a controlled nitrogen environment. The growing δ-TiN films were bombarded with argon ions and illuminated with UV-light. The results demonstrate that the impurity content, the nitrogen to titanium ratio of the films, the microstructure and the crystal alignment are changed using UV-light irradiation during ion assisted deposition.

Low-energy deposition of AI(O) alloys from an electron cyclotron resonance (ECR) plasma offers a scaleable method for the synthesis of thick, high-strength AI layers. This work compares alloy layers formed by an ECR-O2 plasma in conjunction with AI evaporation to O-implanted AI (ion energies 25–200 keV), and it examines the effects of volume fraction of AI2O3 phase and deposition temperature on the yield stress of the material. TEM showed the AI(O) alloys contain a dense dispersion of small y-AbOa precipitates (∼1 nm) in a fine-grain (10–100 nm) fee AI matrix when deposited at a temperature of ∼100°C, similar to the microstructure for gigapascal-strength O-implanted AI. Nanoindentation gave hardnesses for ECR films from 1.1 to 3.2 GPa, and finite-element modeling gave yield stresses up to 1.3 ± 0.2 GPa with an elastic modulus of 66 GPa ± 6 GPa (similar to pure bulk AI). The yield stress of a polycrystalline pure AI layer was only 0.19+0.02 GPa, which was increased to 0.87+0.15 GPa by implantation with 5 at.% O.

There is a need for thin optical coatings that can be produced at low temperatures and have a high reflectance at the extreme ultraviolet (EUV), λ < 1200 Å. Currently, the best such materials are silicon carbide (SiC) and boron carbide sputtered onto optical surfaces. The EUV reflectance of sputtered SiC, however, is not as high as that of the sputtered target materials (sintered or CVD -SiC). More significantly, the reflectance of both sputtered films degrades with time. In previous work the reflectance degradation of the SiC films has been quantified, and efforts to ameliorate it via ion-beam assisted deposition (BAD) were described. Further work on sputtered SiC films is reported, including chemical and structural analysis. In addition, the degradation behavior of sputtered boron carbide is discussed.

Hydrogen etching effects in plasma ion implantation (PII) doping processes alter device structure and implant dopant profile and reduce the retained implant dose. This has particular relevance to the shallow junction devices of ultra large scale integrated circuits (ULSI). Hydrogen etching of semiconductor materials including Si, poly-Si, SiO2, Al, and photoresist films have been investigated. The effects of varying different PII process parameters are presented. The experimental data show that the spontaneous etching by hydrogen radicals enhanced by ion bombardment is responsible for the etching phenomena. A computer simulation is used to predict the as-implanted impurity profile and the retained implant dose for a shallow junction doping when the etching effect is considered.

Plasma ion implantation (PII) hydrogenation has been developed for defect passivation in polycrystalline silicon (poly-Si) thin film transistors (TFTs). A high dose rate PII process using a microwave multipolar bucket (MMB) plasma source and a 12.5 kHz pulse generator achieves saturation of device parameter improvement in 5 minutes, which is much shorter than other hydrogenation methods investigated thus far. These results have been achieved in one sixth the implant time of our previous PII experiments and are in good agreement with our process simulation.

A coating apparatus which combines two material modification techniques, sputter coating and plasma immersion ion implantation, is described. The plasma is generated by an electron cyclotron resonance microwave plasma source. In the upper part of the vacuum chamber, the plasma is confined in a magnetic field by means of a solenoid. In the lower part, a magnetron sputter cathode is mounted which is used for depositing thin films on the sample. The sample is clamped onto a water-cooled sample holder which can be moved in vertical direction. It is connected to a semiconductor-based high voltage pulse generator which provides negative voltage pulses. In this apparatus, a substrate can be pre-implanted by plasma immersion ion implantation, then it can be coated by sputtering. Finally, the sputtered film can be modified by another ion implantation step.

We have employed a 2.45 GHz electron cyclotron resonance (ECR) plasma source to deposit single-crystal thin films of titanium nitride onto MgO substrates of (100) orientation. During deposition the ECR plasma beam delivering a mixture of excited species of molecular and atomic nitrogen ions, strikes a substrate while an electron beam deposits on the same substrate species of titanium. We have studied the formation of films at substrate temperatures of 200, 400, and 600°C, as well as at room temperature. X-Ray diffraction (XRD) revealed that a cubic Bl phase of titanium nitride forms predominantly at all the temperatures explored. Both channeling and Rutherford backscattering spectroscopy (RBS) showed epitaxial layers forming at the temperature as low as 400°C. The minimum relative backscattering yield, χmin decreased as the temperature increased, with the best result of 7.3% obtained for the film deposited at 600°C. Biasing the substrates with either negative or positive voltage at room temperature directly affects film crystallography.