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The reflectivity (R) in the UV–visible range was used to study CdS nanocrystals obtained by implantation of Cd and S ions into SiO2 and subsequent annealing (Ta=300–900°C). We demonstrate that such an analysis can give very useful information about the process of nanocrystal formation and growth. The synthesis of even a small fraction of CdS is readily observable through the appearance of interference fringes since the refractive index of CdS, nCdS, is substantially higher than that of SiO2, nSiO2. Extensive CdS synthesis, resulting in strong fringes, occurs for Ta⩾500°C. In addition, for higher Ta, a peak in R with a maximum at 2.45 eV (R2.45) becomes discernable indicating the formation of larger nanocrystals. It is shown that the blue shift of R2.45 relative to its energy in the bulk CdS closely corresponds to the shift of bandgap, Eg, with crystallite size and may, therefore, be used to estimate the size of the nanocrystals.

Some effects on the optical bands produced by multi energy (highest energy 320 keV) Si and O implantations in (Type III) silica have been measured. We propose that in these samples bands due to the various combinations of oxygen vacancies will increase with increasing Si dose with related O related defects changing at a much smaller rates. In the absorption spectra of samples implanted with O, bands associated with oxygen related defects increase with increasing does, while those due to various forms of O vacancies will change at much smaller rates. Si ions were implanted using implant energies ranging from 35 to 320 keV. O ions were implanted using energies ranging from 35 to 250 keV. The doses at each energy were varied to maintain an approximately constant implanted-species concentration. The implanted layer has an approximately constant concentration for the Si ions that starts 40 nm below the surface and extends to 640 nm, while for the O implanted samples the constant concentration region starts at ∼80 nm from the surface and extend to 640 nm. The Si concentration in the implanted region ranges from ∼0.025 to 0.5 at.% (atomic percent) while the O concentration ranged from 0.035 to 0.7 at.%. The optical absorption was measured from 2.8 to 6.5 eV. We fit the observed spectra for the as implanted samples to the minimum number of bands attributed to intrinsic states in SiO 2 required to fit the data within ±2%. The intensities of these absorption bands were a function of dose and ion species. Bands at 5.01, 5.8 and 6.75 eV increased with increasing Si dose and changed at much smaller rates with increasing O dose, confirming that these bands are related to oxygen vacancies. The band at 4.8 eV increased with increasing O dose confirming that it is due to oxygen related defects, which we attribute to an oxygen molecular ion or peroxy radical.

In principle, boron (B) as a material has many excellent surface properties, including corrosion resistance, very high hardness, refractory properties, and a strong tendency to bond with most substrates. The potential technological benefits of the material have not been realized, because it is difficult to deposit it as coatings. B is difficult to evaporate, does not sputter well, and cannot be thermally sprayed. In this article, first successful deposition results from a robust system, based on the vacuum (cathodic) arc technology, are reported. Adherent coatings have been produced on 1100 Al, CP–Ti, Ti–6Al–4V, 316 SS, hard chrome plate, and 52 100 steel. Composition and thickness analyses have been performed by Rutherford backscattering spectroscopy. Hardness (H) and modules (E) have been evaluated by nanoindentation. The coatings are very pure and have properties characteristic of B suboxides. A microhardness of up to 27 GPa has been measured on a 400-nm-thick film deposited on 52 100 steel, with a corresponding modulus of 180 GPa. This gives a very high value for the H/E ratio, a figure-of-merit for impact resistance of the film. A number of applications are contemplated, including corrosion/abrasion protection for die-casting dies and improved wear resistance for biomedical implants.

Some of the effects of ArF excimer irradiation on the optical bands produced by single energy (4 MeV) and multi energy (highest energy 4 MeV) Ge implantations in silica (Type III) have been determined. Ge ions were implanted at 4 MeV with nominal doses of 1.25, 2.5 and 5.0×1015 ions/cm2. A second series of samples was made using implant energies ranging from 4 to 0.7 MeV. The doses at each energy were varied to maintain an approximate constant implant species concentration with the total number of ions implanted being 10×1015 and 5×1015 cm−2 for concentrations of 0.042 and 0.021 at.%, respectively. The optical absorption was measured from 2.8 to 6.5 eV. The absorption of samples was then measured after 6.4 eV ArF excimer radiation with a fluence of 44 mJ/cm2 per pulse for pulse totals of 3, 11 and 31. We fit the observed spectra for the as-implanted samples and the samples after each ArF exposure to the minimum number of bands attributed to intrinsic states in SiO2 required to fit the data within ±2%. The magnitude and response of these absorption bands to the ArF irradiation was a function of dose and implant conditions.

Metal nanocrystal glass composites were fabricated by single and sequential element implantations of Ag + and Cu + ions into high purity silica. Implantation doses (×10 16 ions/cm 2 ) were 3Ag, 9Cu and 3Ag/9Cu. Composites were analyzed using Rutherford backscattering techniques (RBS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and optical spectroscopy. An optical density spectrum based on the size distribution observed in the sequentially implanted sample for Cu shell and Ag core nanocrystals has been calculated using the dipole and quadrupole terms in a Mie series summation and is compared with the observed absorption spectrum. Results from TEM and EDS as well as the optical simulations demonstrate that Cu shell and Ag core nanocrystals are formed by the sequential implantation of Ag and Cu.

Silica samples were implanted with 4 MeV Ti2+ ions at nominal doses ranging from 0.1 to 5.0×1015 cm−2. Optical absorption was measured from 3.5 to 6.5 eV and in all spectra a local maximum at 5.0 eV and a shoulder at 5.9 eV were observed. A second series of samples was implanted with 4 MeV Si2+ ions at nominal doses ranging from 0.5 to 3.0×1015 cm−2. Based on the literature we assumed that Gaussian bands at 4.8, 5.01, 5.17, 5.88, and 7.15 eV comprised the observed spectra. Using Gaussian functions as basis states, linear fits to the data were performed yielding amplitudes for each band. Between 3.5 and 5.5 eV the fits were within ±3%. At larger energies the fits were unsatisfactory. Non-linear fits with an additional, fully adjustable Gaussian function yielded a band at 6.4 eV with full width at half maximum ∼0.5 eV and reduced the difference between the fit and the data to

Silica samples were implanted with 1.6 and 4 MeV B2+ at nominal doses ranging from 0.5 to 5.0 × 1015 ions/cm2. Sample temperatures during implantation were either 100, 300 or 673 K. Optical absorption was measured from 2.7 to 6.5 eV and in all spectra two maxima were resolved at 5.0 and 5.8 eV. Based on the literature we assumed bands at 4.8, 5.01, 5.17, 5.88, and 7.15 eV comprised the observed spectra. Assuming that the shapes of these bands were Gaussian functions, the data was fitted by allowing the maximum amplitude to be a free parameter. The fit between 2.5 and 5.5 eV was within ±3%. At larger energies the fit was worse. Assuming that there was a band at 6.35 eV reduced the difference between the fit and the data to

A lithium-ion thin-film battery, consisting of the amorphous silicon tin oxynitride anode (`SiTON'), the amorphous lithium phosphorus oxynitride electrolyte (`Lipon'), and a crystalline LiCoO 2 cathode, can be heated at 250°C in air for 1 h which exceeds by far the required solder reflow conditions for electronic circuit assembly. Moreover, the performance of such a battery was found to even improve after the heat treatment. The Li y SiTON profile between 0 and 1.2 V vs. Li was determined in SiTON/Lipon/LiCoO 2 lithium-ion thin-film cells equipped with a Li metal reference electrode. By comparison with a Sn 3 N 4 /Lipon/LiCoO 2 three-electrode lithium-ion thin-film cell, a model for the electrochemical insertion/extraction process of Li y SiTON was suggested. The SiTON/Lipon/LiCoO 2 cells sustained 5 mA/cm 2 between 4.2 and 2.7 V while the anode supplied a reversible discharge capacity of about 340 μA h/mg or even 450 μA h/mg after heating at 250°C in air for 1 h. A long-term cycling stability test of a SiTON/Lipon/LiCoO 2 battery between 3.93 and 2.7 V demonstrated that the Li y SiTON capacity faded only by 0.001% per cycle when charging was stopped as soon as the Li y SiTON potential reached 0 V vs. Li. When this cathode-heavy cell was charged to 4.1 V (Li y SiTON at 0 V vs. Li), a significantly higher reversible discharge capacity was obtained over ∼5000 cycles.

Thin-film cathodes of lithium manganese oxide, 0.3--3 {micro}m thick, were deposited by rf magnetron sputtering of a LiMn{sub 2}O{sub 4} ceramic target onto unheated substrates. The resulting films were dense, {approximately}4.2 g/cm{sup 3}, with a {approximately}50 {angstrom} nanocrystalline spinel structure. The film composition was typically Li{sub x}Mn{sub 2{minus}y}O{sub 4} with y {approximately} 0.3 and 1.2 < x < 2.2. When cycled in a thin-film rechargeable lithium battery, specific cathode capacities of 145 {+-} 23 and {approximately}270 mAh/g were realized for discharge from 4.5 V to either 2.5 or 1.5 V, respectively. The discharge and charge current densities were limited by the resistivity of lithium transport into and through the cathode. After thousands of cycles at 25 C, there was a small increase in cell resistance. After several hundred cycles at 100 C, the discharge curves developed a stable knee at {approximately}4 V characteristic of crystalline LiMn{sub 2}O{sub 4} cathodes. The polarization of the discharge/charge cycles were interpreted in terms of free energy of mixing curves.

Nonlinear optical properties of metal-dielectric composites, such as fractal colloid aggregates and clusters created by ion implantation, are studied. Strong fluctuations of local fields result in huge enhancements of optical nonlinearities in fractal colloid aggregates. The real and imaginary parts of the cubic susceptibility of silver colloid aggregates are measured. It is found that the coefficient of nonlinear absorption strongly depends on the laser wavelength and intensity. Optical limiting effect in fractal silver colloids is observed. Nondegenerate forward four-wave mixing technique is used to investigate the third-order nonlinear susceptibility for nanocomposite material with Au nanocrystals formed inside a SiO 2 glass matrix. The Au nanocrystals are formed by the ion implantation and annealing method that produces very high volume fraction of nanoparticles. The large value |χ(3)|=1.3×10-7 esu is measured. Two characteristic relaxation times, 5.3 ps and 0.66 ps, are estimated from the detuning curve of |χ(3)|, as the probe beam wavelength changes. A novel class of optical materials, microcavities doped with nanostructured fractal aggregates, is also studied. In our experiments, lasing at extremely low pump intensities, below 1 mW, and dramatically enhanced Raman scattering was observed in microcavity/fractal composites.

Ion implantation is a versatile tool for the formation of compound semiconductor nanocrystal precipitates in a host medium with the ultimate goal of producing a uniform size distribution of quantum dots for use in optical devices. Ion implantation was used to form ZnS, CdS, and PbS nanocrystals in both glass and crystalline hosts, and the precipitate microstructures and size distributions were investigated by TEM techniques. The size distributions were found to be significantly different for the three compounds, and several unusual microstructures were observed.

A kinetic 3D lattice Monte-Carlo (KLMC) method is applied to describe nucleation and growth of nanoclusters from a space- and time-dependent supersaturated solid solution of impurity atoms formed by high-dose ion implantation. Within the framework of homogeneous nucleation, the dependence of the nanocluster size distribution on implantation temperature Timp and ion current j is shown. The simulation results are consistent with size and depth distributions of gold nanoclusters in SiO2 observed after implantation at different Timp. The influence of changes of Timp or j during implantation on the size distribution is simulated and the results are discussed with respect to corresponding implantations.

The series Li{sub x}(Mn{sub y}Ni{sub 1{minus}y}){sub 2{minus}x}O{sub 2} for x {le} 1.33 and 0.38 {le} y {le} 0.50 shows a very close relationship to its parent series Li{sub x}Ni{sub 2{minus}x}O{sub 2}. The refined lattice parameters for at least 0.93 {le} x {le} 1.26 are a linear function of the concentration ratio Li/(Mn + Ni) which in turn is proportional to the averaged valence state of the transition metals. Li{sub x}(Mn{sub y}Ni{sub 1{minus}y}){sub 2{minus}x}O{sub 2} is able to reversibly coprecipitate/reinsert Li{sub 2}O and release/absorb O{sub 2}. This self-regulation mechanism seems to always adjust the number of cations to an undisturbed oxygen sublattice according to the rule cations/anions = 1, which holds true at least for temperatures up to 800 C and oxygen partial pressures above 10{sup {minus}5} atm. Samples prepared in air and under O{sub 2} did not show nucleation of Li{sub 2}O, not even for x > 1.0. The series Li{sub x}(Mn{sub y}Ni{sub 1{minus}y}){sub 2{minus}x}O{sub 2} where 0.38 {le} y {le} 0.50 crystallizes in a rhombohedral unit cell (space group R{bar 3}m) for x 1.25. The similarity between Li{sub x}Ni{sub 2{minus}x}O{sub 2} and Li{sub x}(Mn{submore » y}Ni{sup 1{minus}y}){sub 2{minus}x}O{sub 2} strongly suggests a rhombohedral {r_arrow} cubic transition at x {approx} 0.6 for the latter series. Derived from the linear dependence of the X-ray density on the stoichiometric parameter x, an equation was found with which the lithium concentration of Li{sub x}(Mn{sub y}Ni{sub 1{minus}y}){sub 2{minus}x}O{sub 2} thin film phases over the entire range 0 {le} x {le} 1.33 can be determined accurately without extensive ion-beam analysis. XPS measurements on a film with the bulk stoichiometry Li{sub 1.10}Mn{sub 0.39}Ni{sub 0.51}O{sub 2} gave evidence for Mn{sup 4+} and Mn{sup 3+}, but no indication was found for nickel valence states other than Ni{sup 2+}. In order to meet the above-given stoichiometry, the averaged nickel valence state had to increase with film depth.« less

In a lithium thin-film battery, the reversible discharge capacity of a Li 1.12 Mn 0.44 Ni 0.44 O 2 cathode deposited by rf magnetron sputtering and postannealed at 750°C under O 2 could be increased by 80% to 136 μAh/mg when cycled between 4.8-2.5 V instead of 4.2-2.5 V. An 82 atom % Li 1.03 Mn 0.42 Ni 0.55 O 2 /18 atom % Li 2 O (14 vol %) cathode prepared from a rf magnetron sputter-deposited film that was annealed at 700°C under N 2 supplied a reversible discharge capacity of 146 μAh/mg between 5.3-1.5 V. For a given lithium concentration in the cathode during cycling, the magnitude of the chemical potential of sites on the lithium layers (3a sites) in both rhombohedral cathode phases decreased whenever the charge cutoff voltage was raised. This thermodynamic change is attributed to the migration of transition metal ions from the 3b layer sites to vacancies on the lithium layers at high potentials. These transition metal ions also explain the kinetic limitations the cathodes exhibited at higher current densities. Only one rhombohedral phase could be detected by ex situ X-ray diffraction (XRD) measurements over the voltage range 4.6-1.5 V. At 1.5 V, however, possible additional phases might have been present but not detectable due to their low concentration and/or their X-ray amorphousness. The maximum valence state of the transition metal ions of +4 was reached in rhombohedral Li x Mn 0.44 Ni 0.44 O 2 at 4.6 V where about 0.4 Li + per formula units remained on the lithium layers. Such a high lithium concentration between the MO 2 slabs (M = metal ion on 3b layer sites) prevented the phase from developing a unit cell with the extremely small c axis parameter found for NiO 2 and CoO 2 and is believed to be an important prerequisite for the good cycle stability of Li x Mn 0.44 Ni 0.44 O 2 between 4.8-2.5 V

Silica was implanted with Se ions at 4 MeV with nominal doses of 0.1, 0.3, 0.5, 1.0 and 3.0 × 1016 ions/cm2. The optical absorption was measured from 1.8 to 6.2 eV. Bands at 5.9 and 5 eV are observed in the absorption spectra. The magnitude of the absorption increases with increasing dose but the increase is variant with dose. Bands at 2.6, 3.7 and 4.8 eV are attributed to the presence of the Se. The 0.3 and 1.0 × 1016 samples were exposed to 5 eV KrF excimer irradiation with a fluence of 150 mJ/cm2 per pulse for pulse totals of 1.5 J/cm2. Bleaching of the 5 and 5.9 eV bands is observed and is attributed to the bleaching of defects at 5, 5.5 and 5.9 eV.

Silica glass plates (Corning 7940 excimer grade) were implanted sequentially with N+ at 52 keV to different doses, ranging from 0 to 1.2 × 1017 ions cm−2, and then with Fe+ at 160 keV to 6 × 1016 ions cm−2 at room temperature and 4 µA cm−2. The intensity of ferromagnetic magnetic resonance (FMR) absorption and the magnetization calculated by the angular dependence of the FMR field reach maxima at an N/Fe atomic ratio ∼0.2. Two peaks due to Fe 2p3/2 electron are observed at 707.2 ± 0.2 and 710.9 ± 0.2 eV in the x-ray photoelectron spectra. The intensity of the former relative to the latter decreases with increasing the N dose. The conversion electron Mössbauer spectrum reveals the formation of superparamagnetic iron nitride as well as the existence of Fe2+ and Fe3+ in silica when implanting N+ to 7.5 × 1015 ions cm−2 and then Fe+ to 6 × 1016 ions cm−2 at N/Fe = 0.125. These results suggest that sequential ion-implantation of N+ and Fe+ produces iron nitride in silica glasses.

The implantation of Sc(Ti) and O results in the modification of the silica with polarizable Sc(Ti) ions. With annealing the Sc(Ti) ions are incorporated with the O in the network to form a Sc(Ti)–O–silicate layer. Subsequent implantation of Ag into this layer results in the formation of Ag metal nanocluster colloids with significantly modified optical properties compared to samples without the Sc(Ti) ions. The incorporation of the Sc(Ti) results in a shift in the wavelength of the surface plasmon resonance of the Ag nanoclusters and a change in the magnitude of the surface plasmon resonance absorption. The results are interpreted using effective medium theory.

Zinc ion implanted silica with controlled thermal treatments and pulsed laser radiation has been investigated. Optical spectra of the as-implanted silica at higher doses (>3×1016 ions/cm2) and/or the samples annealed in a reducing atmosphere show both Zn clusters and Zn metal colloid formation. The absorption peak at ∼5.3 eV is attributed to the surface plasmon absorption of Zn metal colloids in silica. The oxidized samples with the ion dose ⩾3×1016 ions/cm2 show an absorption peak in 4.3–4.7 eV region implying ZnO quantum dot formation. It is expected that the average size of the ZnO nanoparticles becomes smaller for lower ion dose. Therefore, a blueshift of the absorption peak with lower ion dose can be attributed to the quantum confinement effects. Pulsed laser radiation at 266 nm with energy density of 30 mJ/cm2 causes a brownish coloration in these optically transparent Zn implanted silica substrates. The color formation is an irreversible process. Therefore, it is believed that new chemical species may have formed through photochemical reactions. The results also show that the coloring process is photon energy dependent.

Selenium ions were implanted into fused silica hosts at an energy of 330 keV at fluences of 1 × 10 16 , 3 × 10 16 , 6 × 10 16 and 1 × 10 17 ions/cm 2 . The samples containing 1 × 10 17 ions/cm 2 were annealed at 600, 800 and 1000°C for 1 h in a 5% H 2 + 95% Ar atmosphere. The electronic spectra of the as-implanted sample exhibited an absorption edge near 2.5 eV (550 nm) as compared to 1.95 for bulk trigonal or amorphous selenium. The absorption edge is shifted to the red as the samples were annealed at increasing temperatures. Infrared reflection measurements revealed a decrease in the reflectivity of a peak associated with the LO mode silica and is attributed to ion beam damage. A new peak was also observed near 1050 cm −1 for the as-implanted sample and is assigned to an Si–O-dangling bond vibration formed during ion implantation. This peak vanishes when the samples are annealed at 1000°C indicating that the Si–O–Si linkages have reformed. A redshift of the absorption edge that increases with ion dose and annealing temperature observed in the electronic spectra is attributed to quantum confinement of the photo-generated exciton. This observation is consistent with current models predicting quantum size effects in semiconductor nanocrystals.

Recent demonstrations that large third-order non-linear responses can be achieved in metal nanocluster glass composites are of significant interest because of their potential for use in all optical switching networks. These composite materials exhibit picosecond switching and relaxation times, thermal and chemical stability, high laser damage thresholds, and low two-photon absorption. Ion implantation has been shown to be a useful fabrication method to form these nanoclusters in silica because of its ability to produce thin films in waveguide configurations containing a high volume fraction (>1%) of metal colloids with well-defined vertical and horizontal dimensional control. Using sequential ion implantation of more than one element, we can modify the composition and microstructure of the composites by forming intermetallic metal colloids. In this work, we report on the improved optical response of metallic nanocluster composites formed by sequential implantation of Cd and Ag and Sb and Ag. Characterization of the samples by transmission electron microscopy (TEM) reveals that approximately spherical metallic colloids are formed for all implanted species during the implantation process. Selected area diffraction patterns indicate that the colloids formed are intermetallic in composition. Linear optical absorption measurements made at room temperature in air from 900 to 200 nm show significant changes in both the magnitude and wavelength of the surface plasmon resonance. The formation of intermetallic nanoclusters results in changes in both the linear and non-linear optical properties of the composite material that are not possible with single element colloids alone. The results are explained in terms of effective medium theory.

Silica was implanted with N ions at 4 MeV with nominal doses of 0.1, 0.3, 1.0 and 3.0 × 1016 ions/cm2. Optical absorption, measured from 2.5 to 6.2 eV, had maxima at 5.0 and 5.9 eV whose amplitudes increased with increasing dose. The ratio of the maximum amplitudes of these two bands was invariant with dose. The sample implanted with 1 × 1016 ions/cm2 was exposed to 5 eV KrF excimer photons, 150 mJ/cm2 per 20 ns pulse for totals of 1.5, 15 and 30 J/cm2. Absorption decreased at 5.0, 5.9 and 6.2 eV for all exposures. The decrease in absorption revealed a band at ∼ 4.7 eV that did not bleach. Thes data are compared to similar data of B implanted silica and based on comparison effects specific to N and B are resolved. These differences are attributed to interactions of N with Si and B with O.

Both elemental and compound semiconductor nanocrystals have been formed in insulators by ion beam synthesis. Si nanocrystals in SiO2 give rise to strong optical absorption and intense photoluminescence (PL). The dose dependence of optical absorption provides evidence for size dependent changes in the Si nanocrystal bandgap due to quantum confinement, but the PL results suggest that surface or defect states play an important role in PL. CdS and CdSe nanocrystals have been formed in SiO2 and in Al2O3. Their structure, size, and optical properties are discussed.

Silica composites containing nanometer dimension colloids were fabricated by implantation of Ag ions followed by Cd ions, and by implantation of Cd ions followed by Ag ions. These samples were characterized using transmission electron microscopy and optical spectroscopy. Doses used for the sequential implantations were 6×1016 ions/cm2 of Ag and Cd in a 1 to 1 ratio. Single element colloids were also fabricated by implantation of Ag or Cd using the same nominal dose and implantation energy as the sequential implantations. Sequential implantation of Ag and Cd leads to the formation of multi-component metal nanoclusters and elemental nanoclusters. Different microstructures were obtained depending on the order of implantation. Optical responses are consistent with results expected from effective medium theory.

When Ni+ ions are implanted into silica glasses at a dose of 6 × 1016cm−2 at 160 keV and 3 μA cm −2, nanosize Ni particles (6.5 ± 1.5nm) of spherical shape are produced in the implanted layer, as confirmed by transmission electron microscopy (TEM), electron diffractometry and X-ray photoelectron spectroscopy. The relative intensity of ferromagnetic resonance (FMR) absorption at 298 K increases by a factor of ∼12 after annealing in 4% H2 + 96% Ar for 4 h, although the Ni particle size observed by TEM does not change during this treatment. The mean Ni particle size, obtained from the temperature dependence of FMR intensity, increases from ∼4.5 nm to ∼5.5 nm by annealing. Magnetocrystalline anisotropy is observed in the FMR spectrum, measured at 133 K, of the annealed sample. The increase in FMR intensity by annealing is, therefore, attributed to an increase in the crystallinity of the Ni particles.

Silica composites containing nanometer dimension colloids have been fabricated by implantation of Ag ions followed by Sb ions, and by implantation of Sb ions followed by Ag ions. Doses for the sequential element implantations were in ratios of 9 : 3 Ag : Sb and 3 : 9 Sb : Ag with the total dose held constant at 12 × 1016 ions/cm2. Energies of implantation were 305 keV for the Ag ions and 320 keV for the Sb ions. Single element colloids were also fabricated by implantation of Ag or Sb using the same nominal dose and implantation energy of the sequential implantations. Approximately spherical particles were formed in all implanted samples. Microstructures of the nanoclusters in the various samples were markedly different. Selected area diffraction techniques revealed that alloyed phases of Ag–Sb were formed in some of the sequential implantations. The microstructure and the optical response of the nanocluster glass composites were found to be strongly dependent upon the order of the ion species implanted. The optical spectra of the 3 : 9 Sb : Ag sample displays two resonance peaks indicative of a Ag resonance peak and a resonance peak of an alloyed phase of Ag–Sb. Optical spectra for the 9 : 3 Ag : Sb sample displays two broad absorption peaks indicative of coated particles.

The proper combination of sequential ion implantation and thermal annealing can successfully fabricate binary semiconductor quantum dots (QDs), such as InP, GaP and GaAs QDs. Far-infrared reflectance techniques can be effectively employed to identify the species formed before and after various thermal treatments via probing molecular vibrations and surface phonons of the QDs. This technique is very useful for the characterization of an ultra-thin layer of foreign species on or in the near surface of the bulk substrate materials. In addition, this technique is non-destructive, simple and versatile. The examples given in the present report are InP and GaP QDs formed in fused silica and GaAs QDs formed in fused silica and in [0001] substrates.

Silica was implanted with B and N ions at 4 MeV and Si ions at 5 MeV with nominal doses of 1 × 10 16 ions/cm 2 . The samples were exposed to 245 nm KrF excimer irradiation with a fluence of 150 mJ/cm 2 per pulse for pulse totals of 1.5, 15 and 30 J/cm 2 . The optical absorption from 200 to 450 nm was measured before and after each series of KrF irradiations. Broad peaks at 210 and 245 nm are observed in the absorption spectra. The magnitude of the absorption as well as the photosensitive response is dependent on the implanted ion species. We attribute the differences observed in the absorption of the as implanted samples and their response to KrF irradiation to differences in the ion-solid interactions.

The most widely used anodes in the chloralkali industry are the RuO{sub 2}-TiO{sub 2} coated titanium electrodes. These electrodes have a long life and operate at a low chlorine overpotential and high efficiency. However, upon prolonged use, deactivation of these anodes occurs resulting in high chlorine overvoltages. RuO{sub 2}-TiO{sub 2} electrodes 5,000 {angstrom} thick, which mimic the dimensionally stable anodes in composition and the method of preparation, were prepared and tested for their activity toward the chlorine evolution reaction and subjected to lifetime testing in sulfuric acid solution. Rutherford backscattering spectrometry was used concurrently with electrochemical measurements to analyze the changes in the ruthenium content of the coating. The decrease in electrode activity was found to be closely linked to a decrease in the Ru content, and the measured profiles indicate that the loss takes place across the thin coating. Failure is observed for electrodes with a Ru content below the critical concentration of 3 {times} 10{sup 21} Ru atom/cm{sup 3}, but there is no evidence for the buildup of a pure TiO{sub 2} layer.

Nanometer dimension metal colloids fabricated by sequential implantation of Cd then Ag in silica and by single element implantations of the same elements are characterized by transmission electron microscopy and optical spectroscopy. A nominal dose of 6 × 1016 ions/cm2 as determined by current integration was used for both ions species. The doses used for the sequential implantations were a 1 to 1 ratio of Cd to Ag. Sequential implantation of Cd and Ag leads to the formation of multi-component metal nanoclusters and elemental nanoclusters. The electron diffraction measurements were consistent with the formation of Ag5Cd8 and elemental Ag. With annealing the composition of the nanoclusters shifts to AgCd and elemental Cd. The optical responses are consistent with results expected from effective medium theory.

Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

Au was implanted into the (001) surface of muscovite mica at an energy of 1.1 MeV and at doses of 1, 3, 6, and 10 × 10 16 ions/cm 2 . Absorption spectra of the as-implanted samples revealed a peak at 2.28 eV (545 nm) which is attributed to the surface plasmon resonance of Au colloids. The infrared reflectance measurements show a decreasing reflectivity with increasing ion dose in the Si-O stretching region (900–1200 cm −1 ). A new peak is observed at 967 cm −1 , increases with the ion dose and is attributed to a Si-O dangling bond. Atomic force microscopy images of freshly cleaved samples implanted with 6 and 10 × 10 16 ions/cm 2 indicated metal colloids with diameters between 0.9–1.5 nm. AEM images of the annealed samples showed irregularly shaped structures with a topology that results from the fusion of smaller colloids.

Two series of nanometer dimension metal colloid-glass composites have been fabricated by ion implantation of In in high purity silica glass. One series was implanted at different substrate temperatures while holding the dose constant at 6 × 1016 ions/cm2. Substrate temperatures used were ∼ 100, 273, 463 and 673 K. The second series was implanted with doses of 3, 6, 9, and 12 × 1016 ions/cm2 while holding the substrate temperature constant at 100 K. The properties of these series of samples were measured using backscattering transmission (RBS), transmission electron microscopy (TEM), and optical spectroscopy. RBS results show that a bimodal distribution of the ions occurs for all doses and substrate temperatures. TEM measurements show that spherical colloids are formed and the mean particle size is a function of nominal dose and substrate temperature during implantation. The colloids formed at the higher substrate temperature are amorphous while they have crystalline structure for the lower substrate temperature. The optical spectra exhibit a 1/λ dependence with an absorption peak centered at ∼ 260 nm due to the surface plasmon resonance of the In particles. The optical properties are also a function of nominal dose and substrate temperature during implantation.

A luminescence band at 2.75 eV in silica glass, Corning 7940, excited with 1 keV electron beam was measured as a function of beam current and dose. The initial luminescent intensities at 2.75 eV, taken within 1 s of the beginning of irradiation, were proportional to the beam current in the range 0.8 to 12.7 μA/mm2. The luminescent intensities as a function of dose were observed at current densities of 3.0, 4.8, and 12.7 μA/mm2. The intensities increased linearly for doses

Oxygen ions (O+) were implanted into high purity silica glass, Corning 7940, at liquid nitrogen temperature and at energies of 50, 160 keV and 5 MeV, with a dose range from 1 × 1015 to 3 × 1016 ions/cm2. Helium ions (He+) were also implanted into Corning 7940 at liquid nitrogen temperature and at 35 keV and 160 keV to doses of 1 × 1017 ions/cm2 to compare with O+ implantation. Optical absorption measurements were made on the ion implanted samples in the range of 1.8 to 6.2 eV. In samples O+ implanted at 50 and 160 keV, the optical density at around 2.0 eV was zero, while the optical densities increased with increasing photon energy, and absorption bands at around 3, 5 and 5.8 eV were resolved. Absorption bands at 5 and 5.8 eV were resolved in the 5 MeV implanted sample and their absorbencies were higher by factor of more than 2 than those in the 50 and 160 keV implanted samples. For He+ implanted samples optical density increased as a function of photon energy up to 6 eV, and in addition a band at 5 eV was resolved in every sample. X-band electron paramagnetic resonance (EPR) spectra were measured at 77 K for oxygen-related centers and at room temperature for E′ centers prior to and after ion implantation of samples. Two paramagnetic states, E′ centers and peroxy radicals, were detected after O+ or He+ implantation. The peroxy radical (POR) was the dominant defect in O+ implanted samples, while the numbers of E′ centers and PORs induced in He+ implanted samples were the same. Since the detected numbers of PORs were

We report the infrared, linear and nonlinear optical response of a series of samples formed by the sequential implantation of Ti, Au and O in high purity fused silica. Two samples were implanted with Ti at a nominal dose of 1.2 × 10 17 ions/cm 2 , one of which was then sequentially implanted with oxygen at the same nominal dose as the Ti, and finally, both samples were sequentially implanted with Au at a nominal dose of 6.0 × 10 16 ions/cm 2 . The optical absorption spectra show a peak of the surface plasmon resonance of Au metal particles and a long tail. Strong third-order nonlinear response and two photon stepwise absorption were observed at the wavelength of 775 nm. The optical properties of the samples have changed upon annealing in oxygen at 900°C for two hours. Our results indicate that (1) the annealing results in the recovery of lattice damage and the growth of Au particles; (2) the presence of excess oxygen ions in the glass favors the growth of Au particles; (3) the annealing effects on titanium silicide nanoclusters are different between samples with and without sequentially implanted oxygen. The titanium silicide nanoclusters have dissolved into the silica network and form a TiOSi phase during annealing in the sample with sequentially implanted oxygen.

The interaction of Si, Ti, and Mo atoms with pyrolytic graphite substrates has been studied for evaporated layers of about 100 nm and implanted ions with mean ranges between 2 and 4 nm. In the temperature range from room temperature to 1800 K the thermal diffusion of carbon into the evaporated layers has been studied by Rutherford backscattering spectroscopy while the temperature dependence of the carbide formation has been studied by x‐ray photoelectron spectroscopy. For all three systems stable carbidic phases are predicted by equilibrium phase diagrams. For Ti the formation of TiC is already observed after room temperature implantation, while for Mo annealing to 1200 K is necessary for Mo2C formation. In the case of Si oxygen contamination due to the air transfer after implantation resulted in a mixed SiOxCy phase which only transformed into a SiC phase at temperatures above 900 K, where the oxygen was released. The temperature range of stability of the carbidic layers was found to be correlated to the...

We describe the exploitation of third-order nonlinear optical response — particularly nonlinear absorption and the nonlinear index of refraction — to probe interface dynamics, modifications and relaxation processes in granular materials consisting of metal quantum dots embedded in such dielectrics as fused silica and sapphire. Many features of these materials can be interpreted in terms of the quantum-mechanical model of the “particle-in-a-box”. Electronic and thermal relaxation processes in these novel nanocomposites are dominated by interactions of conduction-band electrons at the boundary between the quantum dot and its surrounding host material. Experimental examples presented include measurements of thermal and electronic relaxation rates, dephasing due to electron collisions at the nanocluster surface, effects of local structural order, changes in the saturation parameter due to chemical modification of the substrate, and one-and two-dimensional heat-transfer effects.

Gold was implanted into randomly oriented single‐crystal CaF2 hosts at doses of 1, 3, 6, and 10×1016 ions/cm2. The modifications of the host resulting from the ion implantation were characterized by measuring the optical response in the 0.0062–6.70 eV range and the changes in surface topography were investigated by atomic force microscopy (AFM). The implantation depth profiles were obtained by Rutherford backscattering measurements. In the as‐implanted samples, a peak is observed at 2.33 eV in the electronic spectra which we attribute to the surface plasmon resonance of gold nanocrystals. The 1.24–0.099 eV range shows no significant difference compared to the spectra of the virgin host. However, the far‐infrared spectra show a splitting in the longitudinal optical phonon and a decrease in the reflectivity of the transverse optical phonon as the ion dose increases. The surface topography changes from one where the scratch and dig features of the virgin substrate are clearly revealed in the constant force A...

Sequential ion implantation of indium and phosphorus into silica combined with controlled thermal annealing has proven to be a novel and effective technique to fabricate InP quantum dots in dielectric hosts. This technique has been applied to synthesize other III–V and II–VI quantum dots. Due to the unique bimodal distribution of the indium in a silica host and a stoichiometric mismatch between the indium and phosphorus concentration profiles, it is believed that two different‐sized InP quantum dots were fabricated. More importantly, we have shown that the infrared reflectance technique is a very effective method to identify the species in the dielectric host and is also a powerful tool to investigate surface phonon modes.

Luminescence spectra and intensities of type I to type IV silicas, excited with a 1 keV electron beam, were measured. Luminescence was measured on type III silica samples implanted with hydrogen or helium ions in a dose range of 10 16 –10 17 /cm 2 with energies in the range of 35–160 keV. Under electron excitation, luminescence bands were observed at 2.75 eV in all samples and bands at 1.9 and 2.2 eV in some samples. The initial luminescent intensities at 2.75 eV were proportional to the beam current in the range of 0.8–12.7 μA/mm 2 and inversely related to the SiOH contents in some silicas and H + implanted silicas. A model is proposed that the transient change of the emission intensities is due to a competition reaction between luminescence center creation and a reaction that diminishes the intensities.

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 × 1016 (Ag + Sb) ions/cm2 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.

A series of nanometer dimension colloids in silica have been fabricated by sequential implantation of Ag and In, and a series by sequential implantation of In and Cu. Energies of implantation were chosen using TRIM 89 to overlay the depth distributions of the sequentially implanted ions. The implanted layers were characterized using Rutherford backscattering spectroscopy, transmission electron microscopy, and optical spectroscopy. Nanometer dimension metal multicomponent colloids were formed. The depth distribution, particle size, and optical response of the composites were found to depend strongly on the ion species implanted and the relative ratio of the ion species. The optical responses are correlated with composition of the multicomponent nanoclusters.

Nanometer dimension metal colloid-glass composites were fabricated by ion implantation of Pb in silica. The samples were implanted with nominal doses of 3, 6 and 12 × 1016 ions/cm2. The optical absorption was measured from 200 to 900 nm and found to increase with increasing dose. The non-linear index of refraction was measured using the z-scan technique. The non-linear response, 1.0 × 10−10 ⩽ n2 ⩽ 6.8 × 10−10 cm2/W increased with increasing dose. Both the linear and non-linear response are due to the presence of the nanometer dimension Pb metal particles.

Near-surface regions of high-purity optical-grade fused silica discs (Corning 7940) were modified by implantation with bismuth ions at 160 and 320 keV to nominal doses ranging from 1 to 9 × 1016 Bi/cm2. Substrate temperatures during implantation were −197, 25 and 600°C with a dose rate of ∼ 3 μA/cm2. Samples implanted with a nominal dose of 6 × 1016 Bi/cm2 were subsequently annealed at temperatures ranging from 500 to 1000°C in oxidizing and inert atmospheres. The distribution of bismuth ions in fused silica was investigated by Rutherford backscattering spectrometry (RBS). The distribution of the implanted species was strongly dependent on the annealing atmosphere, substrate temperature and implantation energy. In general, there was a driving force toward the surface at lower annealing temperatures (between 500 and 700°C) and away from the surface at higher temperatures (T > 700°C) in an oxygen atmosphere. However, there was a driving force only toward the surface in an argon atmosphere. At an annealing temperature of 600°C for 60 min in an oxygen atmosphere, a bi- or multi-modal distribution of bismuth ions in the samples implanted at 160 keV was observed.

We report the linear and nonlinear optical response of bismuth and antimony implanted fused silica with doses of 6 × 10 16 ions/cm 2 . The nonlinear refractive index, n 2 , was measured using a Z-scan technique with a mode locked Ti:sapphire laser operating in 140 fs pulse duration at 770 nm wavelength. It is found that the nonlinear refractive index n 2 of as-implanted samples is large, in the order of 10 −10 cm 2 /W and the n 2 value of Bi as-implanted sample is about 2.4 times lager than that of Sb as-implanted sample. The large n 2 response is attributed to the presence of nanosized metal particles in the implanted layer observed by transmission electron microscopy. We also report the changes of linear and nonlinear optical response when implanted samples were subsequently annealed at temperatures from 500 to 1000 C in argon and oxygen atmospheres. The annealing effect on optical properties is found to be strongly dependent on the annealing atmospheres. Our results indicate that annealing treatment in O 2 affects the local environment of the implanted metal ions and hence the linear and nonlinear optical properties of the metal-dielectric composite. We suggest that a new phase of metal-oxygen-silicate was formed during annealing in O 2 atmosphere.

Fused silica plates were implanted with 58 Ni + at room temperature to a dose of 6 × 10 16 ions cm −2 under the condition of 160 keV and 3 μA cm −2 . The changes in the optical and magnetic properties of Ni + -implanted silica by annealing at 800°C for 4 h in air, N 2 and Ar with 4% H 2 were measured to determine the chemical state of implanted nickel species. The absence of change in the depth distribution of Ni after annealing under these conditions indicates that nickel species did not dissolve in silica. The absorption band due to the surface plasmon resonance of Ni particles at ∼ 3.6 eV decreased and increased on annealing in air and Ar with 4% H 2 , respectively. The intensity of the ferromagnetic resonance signal measured at −196°C was larger than that at room temperature, both increasing with heat treatment. The resonance field depended on the angle between the implanted surface and the applied magnetic field. It is concluded that Ni particles embedded in silica by ion-implantation were magnetized in the plane normal to the ion beam and that super-paramagnetic Ni changed to ferromagnetic Ni during the thermal treatment.

Thin carbon–nitrogen films have been formed by direct impingement of 5–100 eV C+ and N+ or N+2 ions upon solid surfaces, as well as by 5–350 eV N+ bombardment of graphite surfaces. The influences of ion energy, N+/C+ arrival rate, and type of substrate have been studied. The films deposited in this manner are found to be essentially amorphous, with some graphitic regions on the scale of a few nm. Two distinct types of C–N bonding, one attributed to graphitelike local structure (C–N π bonds) and one attributed to C3N4‐like local structure (C–N σ bonds), have been detected by x‐ray photoelectron spectroscopy. Films deposited by dual‐beam deposition and single‐beam nitridation at 75 eV or less exhibit differences in the single‐bonded structure. Total nitrogen concentrations of up to 47 at. % have been measured by Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry. The C KVV Auger line shapes of the two phases have been determined by factor analysis. These line shapes are consistent ...