In this paper our recent work on erbium implantation for optical doping of silicon is reviewed. It is shown that O co-implantation plays a key role both in providing Er with the appropriate chemical surrounding and in allowing the incorporation of high Er concentrations in thick Si layers without the formation of twins and/or precipitates. The luminescence intensity in Er and O co-implanted samples shows a much weaker temperature dependence (a decrease by a factor of 30 from 77K to 300K) than in samples without O (a decrease by 3 orders of magnitude in the same temperature range). This allowed us to observe room temperature photo- and electro-luminescence in Er and O co-doped samples. The temperature dependence of the luminescence in these samples has been determined to be due to non-radiative de-excitation processes. These data are reported and discussed.

Ion beam synthesis of Si and Ge nanocrystals in an SiO2 matrix is performed by precipitation from supersaturated solid solutions created by ion implantation. Films of SiO2 on (100) Si substrates are implanted with Si and Ge at doses 1 × 1016/cm2 - 5 × 1016/cm2. Implanted samples are subsequently annealed to induce precipitation of Si and Ge nanocrystals. Raman spectroscopy and high-resolution transmission electron microscopy indicate a correlation between visible room-temperature photoluminescence and the formation of diamond cubic nanocrystals approximately 2–5 nm in diameter in annealed samples. As-implanted but unannealed samples do not exhibit luminescence. Rutherford backscattering spectra indicate a steepening of implanted Ge profiles upon annealing. Photoluminescence spectra are correlated with annealing temperatures, and compared with theoretical predictions for various possible luminescence mechanisms, such as radiative recombination of quantum-confined excitons, as well as possible localized state luminescence related to structural defects in SiO2. Potential optoelectronic device applications are also discussed.

Composites consisting of nanometer-size metal clusters embedded in a host dielectric can be synthesized by implanting metal ions in either glassy or crystalline substrates. The size and size distributions of the nanoclusters can be controlled by varying the parameters either of the ion-implantation process or subsequent annealing. The nonlinear optical response of these quantum-dot composites can be modeled as that of independent electrons confined to a spherical potential well; experimental data on relaxation times compares favorably with this simple picture. Optical figures-of-merit of these materials suggest potential for applications in nonlinear waveguide devices, particularly since ion implantation is compatible with device-fabrication processes. The basic features of these materials are illustrated from experiments on Cu and Pb clusters in silica.

In this paper optical absorption and photoluminescence (PL) techniques are used to study the optical properties of βFeSi2 layers fabricated by Ion Beam Synthesis (IBS). The way in which the band-gap varies when a small dose of Co is added before Fe implantation is also investigated. Our results indicate that the band-gap for βFeSi2 is direct with a value of O.87eV. When a sufficiently high dose (1×1016cm-2) of Co is implanted prior to Fe we see the appearance of an additional band-gap after annealing at 1173K which we attribute to the formation of a ternary CoxFeySiz, phase. We also show that by placing the sample in a hydrogen plasma it is possible to raise the temperature at which PL occurs in βFeSi2 to ~ 200K.

The optical properties of colorless and transparent crystals can be changed by introducing impurities into the crystal and depend on the elements added. What kind of elements should be added depends on how one modifies the properties. If one wants to put beautiful color on some colorless and transparent crystals such as Al203, SiO2, LiNbO3, etc., it is necessary to produce definite absorption peaks in the visible region for the crystals. In case of using ion implantation for introducing impurities, there is essentially no limitation to the combination of host crystal and impurities.

The effect of ion implantation on the formation and light emitting properties of porous silicon is reported. Si + , F+ ions were implanted into silicon wafers before electrochemical etching process. The experiments showed that porous structure can be formed on the wafer containing amorphous layer, while the porosity distribution with the depth changed greatly compared with the anodized crystalline Si. The implantation of F+ ions greatly affects the formation mechanism. The creation of point defects leads to red-shift in photoluminescence measurements.

Titanium oxide glasses exhibit a significant nonlinear optical response which is attributed to the large polarizability of the Ti ion. Ion implantation is a unique method for incorporating polarizable ions in glass hosts and allows for tailoring the nonlinear optical properties of the material for potential device applications in all optical switching and planar waveguide technology. However, at the molecular level, the linear and nonlinear properties of ion implanted glasses are governed by interactions between the glass host and the implanted ion, radiation damage, and ion-glass chemistry. In order to probe the host-guest interactions, we have measured the infrared and optical spectra for Ti implanted in silica, borosilicate, and aluminosilicate glasses. The infrared and optical spectra indicate that the host-guest interactions and defect concentration differ significantly for the three glasses investigated.

A series of high purity silica samples were sequentially implanted with Ag and Cu ions at energies such that the depth distributions for each of the ions overlapped. The samples were characterized by RBS, TEM and optical spectroscopy. The optical response was found to be dependent on the order of sequential implantation, as well as the relative concentration of the implanted elements. The changes in the optical response are attributed to composition changes of the metal colloids that are formed as a result of alloying of the sequentially implanted metal ions, as well as to changes in the size the colloids.

LiNbO3 single crystals were implanted with Er ions at 3.5 MeV with fluences up to 3*1016 Er/cm2 and subsequently annealed at 1060°C. The warm-up rate of the sample determines whether the implanted, amorphized surface layer recrystallizes via columnar or via layer-by-layer solid phase epitaxial (SPE) growth. The maximum concentration of optically active Er ions is determined to be 0.18 at.%.

The local environment of the polarizable ion in heavy metal oxide glasses is postulated to strongly influence the nonlinear response of these materials. We have previously observed that post-implantation thermal annealing changes the chemical properties of the implanted layer in a different fashion in Pb- and Bi- implanted SiO2. In this paper we report the optical behavior of Sb-implanted SiO2 as a function of annealing temperature and atmosphere. High purity fused silica substrates were implanted at room temperature to a dose of 6 × 1016 ions/cm2, and subsequently annealed at temperatures from 500 to 1000 C in argon and oxygen atmospheres. RBS, optical absorption (1.8 to 6.2 eV), infrared reflectance (450 to 5000 cm-1), and nonlinear index of refraction were measured before and after annealing. The results of these measurements indicate that annealing treatment significantly affects the local environment of the implanted Sb ions, and consequently the optical response.

The preparation of amorphous insulating films containing nanometer-scaled structures of semiconductors has attracted increased attention since the observation of room temperature emission of light from films containing indirect-bandgap semiconductors such as Ge and Si. While most experimental reports on these Si and Ge nano-scale structures have been based on thin films created using sputter-deposition, in this study we have used conventional ion implantation of Ge to create the non-equilibrium mixture of materials that, upon annealing, develops a nano-crystallite phase embedded in the amorphous matrix. The presence of clusters that are difficult to image in TEM, in addition to microcrystallites, is an issue of interest since the source of light emission is still controversial. The second phase is formed from excess amounts of the semiconductor, in this case added by implantation. In this paper the formation and size distribution of the Ge nano-structures was characterized using Raman scattering and transmission electron microscopy (TEM). Similarly to reported sputtered film results, Raman spectra suggest Ge clusters that are not well formed crystallites may be present for anneals at low temperatures and in unannealed films. For annealing temperatures exceeding 600°C, a mixture of amorphous-like clustering and nano-crystallites may result, depending on the volume fraction of Ge. For low dose samples it was found that temperature and time of annealing could be used to manipulate the nucleation behavior of the nano-crystallites.

We have investigated the application of ion implantation technique for introducing activator and co-activator ions into host materials such as ZnS and Zn2SiO4, and have produced phosphors with differing emission peaks throughout the visible range. A number of different ions including, Mn+, Al+ and rare-earth metals have been implanted. Zn2SiO4:Mn showed bright yellow cathodoluminescence. We have demonstrated that by varying the parameters for ion implantation and annealing, a single ZnS sample with emission peaks ranging from violet to yellow can be produced; i.e, chromaticity engineering. In one case, our results indicated that photoluminescence (PL) spectrum of ZnS phosphors shifts from blue to green by increasing the dose of implanted A+ ions. The Al+-implanted ZnS samples showed emission peaks shifting from 440 to 510 nm when the aluminum dose was raised from 1 × 1015 to 1 × 1017 A1+/cm2. Therefore, by activating color centers in thin film phosphors using ion implantation, efficient and low-cost full-color field emission displays can be fabricated on a single layer of host material.

Ion implantation followed by thermal annealing in a reducing atmosphere has been used to create a high density of oriented Si and Ge nanocrystals in (0001) AI2O3. Both types of nanocrystals are three-dimensionally aligned with respect to the AI2O3 matrix, but the orientational relationships are different, and the two types of nanocrystals have different shapes in AI2O3. Implantation of Si and Ge in fused silica also produces nanocrystals, but in this case, the nanocrystals are randomly oriented relative to each other.

An erbium-fluorine complex is 100 times more effective than an erbium-oxygen complex in generating light emission at 1.54 µm in Si:Er. The luminescence light intensity is linearly proportional to the total retained F atoms in Si after heat treatment. F enhancement in light emission in Si:Er is eventually limited by the damage associated with high dose F implantation. The optimum annealing temperature to achieve the maximum intensity is found to decrease slightly from 1000ºC to 800ºC as the initial F implanted concentration increases. The Si:Er heat treatment process and the optimum processing window are determined by the interaction of three different processes: damage recovery/complex formation, F out-diffusion and Er-F complex dissociation.

MeV implantation of Au has been used to create a high density of Au nanoclusters in the near surface of fused silica. Measurements of the nanocluster size and size distribution under various implantation/annealing conditions are presented and correlated with measurements of optical absorption arising from surface plasmon resonance absorption by the Au nanoclusters in fused silica. Preliminary measurements of the nonlinear refractive index are included.

Ion implantation into steels with a martensitic microstracture is reviewed and discussed in terms of different implanted species and observed changes in the structure. Both single ion and dual ion implantation treatment are included. The disability of the nitrogen ion implantation to improve the tribological characteristics of steels with a martensitic microstructure can be overcome by dual implantation of titanium and carbon, for example. Results of tribological tests on samples in which titanium is replaced by chromium are more controversial, although changes in the sliding characteristics were observed. Dry sliding on the samples implanted up to 1018 ions/cm2 is totally different by nature and -based on the reported results- associated with the formation of carbon precipitates on the surface. The thermal stability of implanted nitrogen and carbon in MЗ high-speed steel was examined and nitrogen was shown to be less stable than carbon. Mechanical and tribological properties were further changed by heat treatment after ion implantation, which indicates that temperature is also a critical parameter during ion implantation.

Surface treatment experiments using intense pulsed ion beams have demonstrated new capabilities for materials surface treatment. These experiments have confirmed corrosion resistance, surface hardening, amorphous layer and nanocrystalline grain size formation, metal surface polishing, controlled melt of ceramic surfaces, surface cleaning and oxide layer removal by rapid melting and resolidification. Deposition of beam energy in a thin surface layer allows melting of the layer with relatively small energies (1-10 J/cm2) and allows rapid cooling (109-1010 K/sec) and resolidification of the melted layer by thermal diffusion into the underlying substrate. At higher intensities (≥20 J/cm2), this technology can provide rapid ablation of material from targets followed by rapid, congruent deposition of polycrystalline thin films on substrates. This technology uses high energy pulsed (40–400 ns) ion beams to directly deposit energy in the top 2–20 micrometers of the surface of materials.

Selected usages of ion beam processes within the U.S. Department of Defense (DoD) are discussed in terms of their technical merits, their current status, and the various factors governing their acceptance within the DoD user community.

Ion Beam Assisted Deposition (IBAD) involves vacuum deposition processes which incorporate concurrent energetic ion bombardment and material deposition. The effects of the ions are to promote adhesion, densify the films, and to help chemically incorporate reactive ions into the coatings. Examples of IBAD studies that have progressed from R&D to production status are presented with a discussion of the technical and marketing factors influencing their commercial acceptance.

The tribological properties for pulsed W+C and Mo+C dual implanted H13 steel are given in this paper. The pulsed ion of W, Mo and C were implanted at 40KV to dose of (3~12)×1017/cm2 with ion flux from 25 to 100µA/cm2 using MEVVA implanter. The results show that the wear resistance life and hardness of the dual implanted H13 steel increase 2~3 times. The comparison of dual implantation with single implantation shows that the dual implantation is better. The tribological properties of W+C dual implanted H13 steel is better than Mo+C dual implanted H13 steel. The TEM and X-ray diffraction analysis show that the super high hardening dispersed phases of MoC, MoCx, WC and W2C were formed during ion implanting. The iron compounds of tungsten and molybdenum and iron carbides were obtained also. That is, the strengthening effect in H13 steel of phases MoC and WC is better than FeMo, Fe3Mo2, Fe2W and Fe7W6.