Optical nonlinearity of metal nanoparticle composites fabricated by negative ion implantation

Optical absorption and nonlinear absorption were studied for Ag nanoparticle composite. Negative Ag⁻ ion with 60 keV were applied for implanting into amorphous-SiO₂ at a flux 3 μA/cm² to total fluences ranging from 3 × 10¹⁶ to 1 × 10¹⁷ ions/cm². Absorption spectra of Ag-implanted amorphous-SiO₂ showed a surface plasmon peak resulting from formation of nanoparticles. The strength of the resonance reflected from the local electric field inside the nanoparticle induced by an external electric field. Nonlinear optical constants were evaluated by the z-scan method with a tunable femtosecond laser system. The strength of the nonlinearity also reflected from the local electric field. Nonlinear absorption coefficients exhibit a maximal value of −3.6 × 10³ m/GW for Ag:SiO₂ at 420 nm (2.95 eV), around the surface plasmon resonance.     

Saturation effects observed in high fluence heavy ion implantation at few tens of keV

Effect of implantation fluence on the total number of metal atoms incorporated in a host matrix at few tens of keV beam energy has been studied experimentally using Rutherford backscattering spectrometry (RBS) as well as using simple calculations, taking Au and Ag ions for host matrices Si and silica glass. In all the cases, calculations showed that the total number of retained metal atoms are identical to the implantation fluence upto 3 × 10¹⁶ ions cm⁻² above which the metal content retained in the matrix shows a saturation. The variation in the number of metal atoms as a function of the implantation fluence extracted from the RBS measurements has been found to be in good agreement with the results of the calculation expect for the high fluence implantation case of Ag in Si. This observed difference is attributed to the irradiation induced in-diffusion of Ag atoms in Si matrix due to the low diffusion activation energy of Ag in Si. Effect of saturation on the number of metal atoms incorporated in the matrix is reflected in the Raman scattering data of the implanted Si samples as well as the optical absorption data of the implanted silica glass samples.     

Optical properties of Cu and Ag nanoparticles synthesized in glass by ion implantation

Metal nanoparticles synthesized by sequentially ion-implanted Ag and Cu into silica glasses have been studied. The implantation doses (×10¹⁶ ions/cm²) were 5Ag, 5Cu and 5Ag/5Cu, respectively. The optical and microstructural properties of the nanoparticles were characterized by optical absorption spectra and transmission electron microscopy (TEM), respectively. Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 1064 nm of wavelength using Z-scan technique. Results in this paper indicate that the nonlinear refractive index for the Ag/Cu implanted system has a higher value compared to single Ag or Cu implantation nanoparticles.     

Optical nonlinearities of Au nanocluster composite fabricated by 250 keV ion implantation

Metal nanocluster composite glass prepared by 250 keV Au ions into silica with dose of 1 × 10¹⁷ ions/cm² has been studied. The microstructural properties of the nanoclusters are characterized by optical absorption spectra and transmission electron microscopy (TEM). Third-order optical properties of the nanoclusters are studied by the Z-scan technique under 1064 nm and 532 nm excitations. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility are deduced. The results of the investigation of nonlinear refraction using the off-axis Z-scan configuration are presented and the mechanisms responsible for the nonlinear response are discussed. The third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 1.6 × 10⁻⁷ esu at 532 nm and 1.3 × 10⁻⁷ esu at 1064 nm.     

金属离子注入聚合物光电特性研究

采用MEVVA离子注入机引出的Cu和Ni离子注入聚酯薄膜，注入后的聚酯膜极大降低了聚酯膜的电阻率。注入表面紫外线和红外线吸收特性明显增强。用透射电子显微镜观察注入聚酯膜的横截面，TEM观察表明，在注入层中形成了纳米金属颗粒和富集的碳颗粒。注入层的结构的变化和新相的形成引起了聚合物表面物理和化学特性的改变，进而讨论了金属离子注入聚酯膜的改性机理。     

Planar optical waveguides in Nd:BSO crystals fabricated by He and C ion implantation

Planar optical waveguides in Nd:BSO crystals were fabricated by the implantation of 500 keV He ions and 6.0 MeV C ions at two different substrate temperatures. The guiding modes were measured by the prism-coupling method with a He-Ne beam at 633 nm. The intensity calculation method (ICM) and reflectivity calculation method (RCM) were used for reconstructing refractive index profiles. The near-field intensity distribution of the waveguide, formed by He and C ions implanted after annealing at 300 °C, was measured by the end-face coupling setup. It was in reasonable agreement with the intensity of the waveguide mode simulated by the finite-difference beam propagation method (FD-BPM). The absorption spectra of the sample with He ions implanted at fluences of 3 × 10¹⁶ ions/cm² were measured using a spectrophotometer.     

Refractive indices and thicknesses of optical waveguides fabricated by silicon ion implantation into silica glass

Planar optical waveguides formed by Si ion implantation into PECVD SiO₂ have been characterized by the dark mode spectroscopy method at a wavelength of 0.6328 μm. The measured effective index values of the guided modes have been used to investigate the optical properties of the core layers of the waveguides after different pre-implantation treatments. It was found that annealing the specimens before implantation, affected both the refractive index and thickness of the core layers. In the annealed specimens a thicker core layer and a larger relative refractive index difference between the core and the buffer layer resulted.     

Nonlinear optical properties of Ag nanocluster composite fabricated by 200 keV negative ion implantation

Metal nanocluster composite glass prepared by 200 keV Ag ions' implantation into silica with dose of 2 × 10¹⁷ ions/cm² has been studied. The formation of sandwiched nanocluster-nanovoid-nanocluster structures has been evidenced by in situ transmission electron microscopy experiment (TEM). Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 532 nm and 1064 nm of wavelength by the Z-scan technique. The third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 4.0 × 10⁻⁸ esu at 532 nm and 9.0 × 10⁻⁸ esu at 1064 nm, respectively.     

Microstructure and friction performance of copper film fabricated by ion implantation assisted electroless plating on PTFE

Abstract

The polytetrafluoroethylene (PTFE), which was implanted with Ni ion to different energy and doses, fabricated metallic structures by selective electroless copper plating. The characteristic and microstructure of the copper film were studied using SEM and X-ray diffraction. Friction performance of the interface between copper film and basal body of PTFE was tested with a CETR UMT-2 (CETR Co., Campbell, CA, USA) multifunction micromechanics instrument. The test loads were 10, 20 and 40 N, while the line velocity was 8 mm s^?1, and the frequency of data acquisition was 1 Hz. The Ni ion implantation replaces the complicated electroless plating surface pretreatment, and it is an assisted technique of electroless plating of copper on the surface of PTFE and plate Cu directly on its surface. Continuous, prepressing and uniformity plating was obtained with proper technique parameters and the dosage of Ni⁺. The frictional performance comprehensive property of copper film was remarkably influenced by different plating methods, annealing treatment and testing loads under unlubricated condition. The friction coefficients and wear rates changed with the varied load. Annealing treatment improves the tightness and uniformity of the copper film, while it decreases its cavity. Friction performance of copper film was thus increased. The mechanisms of friction and wear of copper film under different test conditions are also discussed.     

Optical investigation of nitrogen ion implanted bulk ZnO

Nitrogen ions were implanted into melt-grown ZnO (0001) substrates and subsequently annealed at 800 °C under an oxygen ambient. The photoluminescence spectrum of N⁺-implanted ZnO excited by a He-Cd laser exhibited donor-acceptor pair (DAP) transition emission at 385 nm with a full width at half maximum of 30 nm at 10 K. The DAP emission is associated with the acceptor energy of nitrogen in ZnO, calculated to be 170 meV. Defect-related red emission at about 610 nm observed in N⁺-implanted ZnO was due to the residual damage from the implantation step because it was also observed in Ar⁺-implanted ZnO but not in un-implanted ZnO annealed at 800 °C under the same oxygen ambient.     

Formation of aligned silver nanoparticles by ion implantation

Synthesis of metal nanoparticles by ion implantation has a number of advantages. Nevertheless, certain remaining difficulties must be overcome in order to optimize the characteristics of ion-implanted nanocomposites. The principle among these are the lack of control over the size distribution and position of the precipitates within the implanted layer. Two-dimensionally ordered arrangements of Ag nanoparticles are formed in Ag-implanted silica glass by post-implanted Cu ions. The spherical Ag nanoparticles are formed to align at the same deep depth in the silica. Cross-sectional transmission electron microscopy revealed that the Ag nanoparticles are a size of 35-48 nm in diameter. The evolution of nanoparticles is characterized by transmission electron microscopy.     

Accelerator based synthesis of hydroxyapatite by MeV ion implantation

Accelerator based MeV ion implantation of Ca²⁺ and P²⁺ into the titanium substrate to form hydroxyapatite (HA) has been carried out. Calcium hydroxide was formed after heating the calcium implanted titanium in air at 80 °C for 3 h. Upon subsequent annealing for 5 min at 600 °C HA was formed on the surface. Penetration depth of the HA layer in this method is much higher as compared to keV ion implantation. By elemental analysis, Ca/P ratio of the HA was found to be 1.76 which is higher than the ideal 1.67. This higher Ca/P ratio is attributed to the higher penetration depth of the MeV technique used.     

Formation of uniaxially strained SiGe by selective ion implantation technique

Uniaxially strained SiGe layers were fabricated with a newly developed selective-ion-implantation technique. The SiGe layer was grown on the Si substrate, into which laterally selective ion-implantation with stripe pattern was carried out prior to the SiGe growth. A strain-relaxation of the SiGe layer was largely enhanced due to ion-implantation-induced defects selectively in the ion-implanted area while it was hardly enhanced in the neighboring unimplanted area. However, micro-Raman mapping and X-ray diffraction reciprocal space mapping measurements obviously revealed that the relaxed SiGe in the implanted area remarkably influenced a strain state of the neighboring strained SiGe in the unimplanted area, that is, the strain along the stripe line direction was highly relieved due to the stress caused by the neighboring relaxed SiGe while the strain in the direction perpendicular to the line was well maintained. As a result, highly asymmetric strain state, that is, uniaxial strain was realized, where 4 times different relaxation ratios in the two directions were observed. These results indicate that the selective-ion-implantation technique developed in this study has a high potential to realize uniaxially strained Si/Ge channel devices with high mobility.     

Honeycomb voids due to ion implantation in germanium

For future semiconductor devices, germanium layers are very attractive due to their high carrier mobility with ion implantation remaining the dominant method for forming pn junctions. Yet, implantation of heavy ions above a critical dose causes inadmissible surface roughness and formation of voids. To understand the main factors of influence, a comprehensive study on void formation was performed with different ions (BF₂, P, Al, Ga, Ge, As, Sb) implanted at various doses, dose rates, and energies. It was found that the dose is the most important parameter for void formation. The critical dose was determined to be 2 · 10¹⁵ cm^− 2 for As, 2 · 10¹⁵ cm^− 2 for Ga, and 5 · 10¹⁴ cm^− 2 for Sb, respectively. For ions with lower mass (BF₂, P, Al), no or only negligible surface roughening was observed.     

Rapid degradation of biomedical magnesium induced by zinc ion implantation

The degradation rate is important to biodegradable magnesium materials. In this study, Zn is implanted using a cathodic arc source into pure magnesium at an accelerating voltage of 35 kV. The nominal ion implant fluence is 2.5 × 10¹⁷ ions cm⁻². After Zn implantation, the degradation rate in simulated body fluids is increased significantly. It is postulated that because Zn exists in the metallic state in the implanted layer, the galvanic effect between the Zn rich surface region and magnesium matrix induces the observed accelerated degradation.     

Properties of implanted PET by W ion using MEVVA implantation

Polyethylene terephthalane (PET) has been modified with W ions from a metal vapour arc source (MEVVA). W ions were implanted at 136 keV to doses ranging from 5×10¹⁵ to 2×10¹⁷/cm². The surface of the implanted PET darkened with increasing ion dose, when the metal ion dose is greater than 1×10¹⁷ cm⁻² the colour changed to metallic bright. The surface resistance obviously decreases with increasing dose. The resistivity is stable after long-term storage. TEM photos revealed the presence of W nanometer particles on the surface resulting from the high does implantation. The depth of implanted layer is approximately between 180 and 100 nm for W-implanted PET to doses of 2×10¹⁷/cm² and 5×10¹⁶/cm², respectively. The conductivity and wear resistance have been improved significantly due to W ion implantation. It can be seen that nanometer particles of W precipitation, and carbides have been formed in the implanted layer. The nano-hardness of the implanted PET has been measured by a nano-indenter. The results show that the surface hardness, modulus and wear resistance could be increased.     

Ag、Cu离子先后注入SiO_2玻璃后形成纳米颗粒的光学性质研究

采用由金属蒸汽真空弧离子源(MEVVA)引出的强束流脉冲Ag、Cu离子,先后注入到SiO2玻璃。注入的剂量均为5×1016ions/cm2,Ag的加速电压为43kV,Cu的加速电压为30kV。光学吸收谱显示吸收峰的位置在442nm,可以推测Ag、Cu在SiO2玻璃表层形成了纳米合金。借助X射线光电子能谱仪(XPS)考察注入样品的价态分布,观察到Ag、Cu仍大多以金属态形式存在。对样品进行退火后,发现光学透射率发生了明显的变化。     

Mass transfer of metal ion implantation into metal targets at elevated temperatures

A mass transfer model for metal ion implantation into a metal target at elevated temperatures has been built up based on transport of ions in matter and radiation enhanced diffusion. It is used to calculate concentration-depth profiles and compositional changes of the implanted species. The ion implantation at elevated temperatures was simulated by a dynamic Monte Carlo (MC) method, which takes into account a local saturation in the crystalline target by using a maximum atomic fraction allowed in the matrix. For the diffusion process, the transport of the implanted species was obtained from the diffusion equations for the implanted species and nonequilibrium vacancies. The radiation enhanced diffusion coefficient was obtained by taking into account linear annealing of the defects. A nonequilibrium vacancy source function and surface sputtering were introduced into the diffusion equations. Concentration-depth profiles of Cr, Fe and Ni ions implanted into Al at a temperature range from 200 to 510 °C were calculated. The calculated results principally were consistent with measured concentration-depth profiles obtained by Rutherford backscattering spectroscopy (RBS). In some cases deviations occur, which are discussed.     

Structural and optical properties of Cu nanoparticles embedded in Si3N4/Si by ion implantation

Cu nanoparticles (NPs) have been fabricated in Si₃N₄/Si by 45 keV Cu ion implantation at a dose of 1 × 10¹⁷ cm⁻², and followed by thermal processing at 500–700 °C in air. Techniques, such as atomic force microscopy and X-ray diffraction are used to confirm the formation and evolutions of Cu NPs. The surface plasmon resonance of Cu NPs has been investigated by reflection spectroscopy. The orange–red luminescence band (600 nm) with high fluorescence quantum efficiency has been observed in Cu NPs, and its possible mechanism has also been discussed.