Ag Ion Implantation Research Articles

EPR study of defects produced by MeV Ag ion implantation into silicon

The damage produced by implanting (1 1 1) Si wafers with 4 MeV Ag ions at implantation temperatures of 210, 350 and 400 K has been investigated by electron paramagnetic resonance as a function of implantation fluence in the range 5 × 10 12–2 × 10 15 Ag cm −2. For each implantation temperature, at low ion fluences the EPR spectra show the presence of the point defect centres Si-P3 (neutral 4-vacancy) and Si-P6 (di-interstitial) as well the so-called Σ defect complexes. As the implantation fluence is raised the population of P3 centres goes through a maximum while the Σ centre resonance is gradually replaced by the spectrum of the well-known Si-D centre of a-Si. For implantation at 210 K the total Σ+D centre concentration increases linearly with implantation fluence up to the point at which an amorphous layer is formed; however raising the implantation temperature causes the dependence of the Σ+D concentration on implantation fluence to become increasingly sublinear with the result that the production of a given level of damage requires a larger implantation fluence. The results are discussed in the context of a previous study of the implantation damage in the same samples by optical reflectivity depth profiling [Mat. Res. Soc. Symp. Proc. 540 (1999) 31].

Characterization of Nanoclusters in MgO Created by Means of Ion Implantation.

ABSTRACTMetal nanoclusters (NCs) of lithium, zinc, silver and gold embedded in MgO were created by means of ion implantation of Li, Zn, Ag and Au ions into single crystals of MgO(100) and subsequent thermal annealing. Nanoclusters of the compound semiconductor CdSe were obtained by implantation of both Cd and Se ions. Solid noble gas clusters were formed by Kr ion implantation. Optical and structural properties of the NCs were investigated using optical absorption spectroscopy (OAS), high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). The mean nanocluster size is estimated from the broadening of the Mie plasmon optical absorption bands using the Doyle formula. These results are compared with the NC size as obtained from XRD (using the Scherrer formula) and from direct XTEM observations. The three methods are found to be in reasonable agreement with a mean size of 4.0 and 10 nm found for the Au and Ag clusters, respectively. Using TEM observations, the relative interface energies of MgO//Au and MgO//Ag interfaces are also determined. In the case of MgO//Au, they are found not to be in agreement with theoretical predictions in the literature. CdSe nanoclusters were found to adopt different crystal structures dependent on the size. Small ones (<5 nm) appear to have a rock salt structure, larger ones the sphalerite structure. The solid krypton NC's are under high pressure. The pressure of individual Krypton bubbles was determined from the moiré fringes

The nano-structure and properties of Ag-implanted PET

Polyethylene terephthalate (PET) has been modified by Ag ion implantation with a dose range from 1×10 16 to 2×10 17 ions/cm 2 using a metal vapor vacuum arc source. The surface morphology was observed by atomic force microscopy. The Ag atom precipitation was determined. The change of the nano-structure of Ag-implanted PET was observed using a transmission electron microscope. It is believed that this change causes an improvement of the conductive properties and wear resistance. The electrical properties of PET were also changed after Ag ion implantation. The resistivity of implanted PET decreased with an increase in ion dose. When an Ag ion dose of 2×10 17/cm 2 was selected, the resistivity of PET could be less than 0.02 Ω m. The surface hardness and modulus increased compared to the untreated PET. The hardness and modulus of Ag-implanted PET with a dose of 2×10 17/cm 2 is 2.2 and 7.3 times greater than that of pristine PET, respectively. The area of a cutting groove for Ag-implanted PET is narrow and shallow compared to the unimplanted PET. Thus wear resistance improved greatly. The Ag ion beam modification mechanism of PET will be discussed.

Nanometer structure and conductor mechanism of polymer modified by metal ion implantation

Polyethylene terephthalate (PET) has been modified by Ag, Ti, Cu and Si ion implantation with a dose ranging from 1×1016 to 2×1017 ions/cm2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been improved by metal ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. The results show that the conductive behavior of a metal ion implanted sample is different from Si-implantation samples. In order to understant the mechanism of electrical conduction, the structures of implanted layer were observed in detail by XRD and TEM. The nano carbon particles were dispersed in implanted PET. The nano metallic particles were built up in metallic ion implanted layers with dose range from 1 × 1016 to 1 × 1017 ions/cm2. The nanometer metal net structure was formed in implanted layer when a dose of 2 × 1017ions/cm2 is reached. Anomalous fractal growths were observed. These surface structure changes revealed conducting mechanism evolution. It is believed that the change would result in an improvement of the conductive properties. The conducting mechanism will be changed with increasing metal ion dose.

Electrical properties of polymer modified by metal ion implantation

Polyethylene terephthalate (PET) has been modified by Ag, Cr, Cu and Si ion implantation with a dose range from 1×10 16 to 2×10 17 ions cm −2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been changed after metal ion implantation. The resistivity of implanted PET decreased obviously with an increase of ion dose. When metal ion dose of 2×10 17 cm −2 was selected, the resistivity of PET could be less than 10 Ω cm, but when Si ions are implanted, the resistivity of PET would be up to several hundred Ω cm. The results show that the conductive behavior of a metal ion implanted sample is obviously different from Si implantation one. The changes of the structure and composition have been observed with transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface structure is varying after ion implantation and it is believed that the change would cause the improvement of the conductive properties. The mechanism of electrical conduction will be discussed.

Nonlinear optical waveguides produced by MeV ion implantation in LiNbO3

We analyze microstructure, linear and nonlinear optical properties of planar waveguides produced by implantation of MeV Ag ions into LiNbO3. Linear optical properties are described by the parameters of waveguide propagation modes and optical absorption spectra. Nonlinear properties are described by the nonlinear refractive index. Operation of the implanted crystal as an optical waveguide is due to modification of the linear refractive index of the implanted region. The samples as implanted do not show any light-guiding. The implanted region has amorphous and porous microstructure with the refractive index lower than the substrate. Heat treatment of the implanted samples produces planar light-guiding layer near the implanted surface. High-resolution electron microscopy reveals re-crystallization of the host between the surface and the nuclear stopping region in the form of randomly oriented crystalline grains. They make up a light-guiding layer isolated from the bulk crystal by the nuclear stopping layer with low refractive index. Optical absorption of the sample as implanted has a peak at 430 nm. This peak is due to the surface plasmon resonance in nano-clusters of metallic silver. Heat treatment of the samples shifts the absorption peak to 545 nm. This is more likely due to the increase of the refractive index back to the value for the crystalline LiNbO3. The nonlinear refractive index of the samples at 532 nm (of the order of 10−10 cm2 W−1) was measured with the Z-scan technique using a picosecond laser source. Possible applications of the waveguides include ultra-fast photonic switches and modulators.

Synthesis of metal/polymer composite films by implantation of Fe and Ag ions in viscous and solid state silicone substrates

We investigated a process of metal phase synthesis in a polymer by high-dose implantation of metal ions in silicone substrates at constant current density. The samples were obtained by implantation of 40 keV Fe + and 30 keV Ag + ions in both viscous (at the moment of implantation) and solid state silicone polymers. The structural and physical properties of the irradiated polymers were investigated by TEM, magnetic resonance and absorption UV–VIS spectroscopy. The strong influence of the relaxation state of the silicone target on the metal phase growth, morphology and sizes of iron and silver nanostructures, as well as the magnetic and optical properties of the synthesized metal/polymer composite films are shown experimentally.

Contact angle lowering of polystyrene surface by silver-negative-ion implantation for improving biocompatibility and introduced atomic bond evaluation by XPS

Negative-ion implantation technique is expected as an effective surface modification method for insulators of polymer, since in negative-ion implantation into insulators the charge-up potential of the surface is in several volts. Polystyrene dishes were implanted with Ag − ions in an ion energy range under 30 keV in order to bring hydrophilic property to their surface for improving surface biocompatibility of cell adhesion property, and contact angles to water were measured. Contact angle was found to be lowered to 73° by the Ag-ion implantation from an original value of 86°, and it decreased with increase in both ion dose and ion energy below 20 keV. Atomic bonds of C–O, CO, and OC–O were introduced by ion implantation, these were increased in number with increase in dose and energy of implantation. These atomic bonds were considered to bring the hydrophilic property to the polystyrene surface. Human umbilical vascular endothelial cell (HUVEC) was cultured on each sample with a 199 medium. The cell growth and attachment were observed only for Ag-implanted surfaces.

Third order optical nonlinearity of colloidal metal nanoclusters formed by MeV ion implantation

We report the results of characterization of nonlinear refractive index of the composite material produced by MeV Ag ion implantation of LiNbO 3 crystal ( z-cut). The material after implantation exhibited a linear optical obsroption spectrum with the surface plasmon peak near 430 nm attributed to the colloidal silver nanoclusters. Heat treatment of the material at 500 ∘C caused a shift of the absorption peak to 550 nm. The nonlinear refractive index of the sample after heat treatment was measured in the region of the absorption peak with the Z-scan technique using a tunable picosecond laser source (4.5 ps pulse width). The experimental data were compared against the reference sample made of MeV Cu implanted silica with the absorption peak in the same region. The nonlinear index of the Ag implanted LiNbO 3 sample produced at five times less fluence is on average two times greater than that of the reference.

An optical study of silver particles fabricated by ion implantation in a silicon polymer

Polymer layers containing Ag were fabricated by 30 keV Ag-ion implantation into viscous and solid-state silicone organic matrices. The optical properties of the composites are presented by means of transmission spectra in the range from 250 to 870 nm for different ion doses of 0.05- 1.8 1017 ions cm-2. The absorption at the wavelength of the surface plasmon resonance of Ag particles at doses higher than 1016 ionscm-2 was determined. A remarkable red shift in the absorption maximum from 405 to 505 nm was observed with increasing dose and with a change in the viscosity of the irradiated polymer. The optical spectra of the implanted polymer were analysed using the Maxwell-Garnett effective-medium theory. The dose dependences of the calculated value of the metal volume fraction in the implanted polymer suggest the possibility of achieving a higher degree of coagulation of introduced metal ions to metal particles in a viscous polymer than in a solid-state matrix.

AG:CD and CD:AG implantations into high purity silica

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 6×10 16 ions/cm 2 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.

Ag : Sb and Sb : Ag implantations into high purity silica

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.

Annealing behaviour of c-SiO 2 implanted layer distributed with high density Ag nanoparticles

High volume density Ag nanoparticles embedded in c-SiO 2 matrix have been prepared by Ag ion implantation at an energy of 200 keV and a current density of about 20 μA/cm 2 to a nominal dose of 6.7 × 10 16ions/cm 2 at RT. Bright-field transmission electron microscopy (TEM) image indicates that Ag nanoparticles show two groups of sizes: the larger diameter is about 25 nm and the smaller is less than 10 nm. RBS spectra show that the distribution of implanted Ag atoms is bimodal which is associated with the two groups of nanoparticles above. Thermal stability of the implanted layer which consists of Ag nanoparticles, dissolved Ag atoms and c-SiO 2 matrix has been investigated by RBS, TEM and Raman spectroscopy. RBS spectra prove that little migration of Ag atoms is found and Ag nanoparticles are considerably stable at 300°C annealing. Though the obvious change in the distribution of Ag is observed at 400°C annealing in RBS spectra, TEM image identifies that both the larger and the smaller Ag nanoparticles still exist at relatively stable state. Following 750°C annealing, Ag atoms drastically move, and furthermore, the bimodal character of the distribution disappears. On the other hand, the amorphized SiO 2 implanted layer recrystal after 300°C, 400°C annealing.

Study of the Effects of MeV Ag, Cu, Au and Sn Implantation on the Optical Properties of LiNbO3

ABSTRACTWe present the results of characterization of linear absorption and nonlinear refractive index of Au, Ag, Cu and Sn ion implantation into LiNbO3. Silver was implanted at 1.5 MeV to fluences of 2 to 17 × 1016/cm2 at room temperature. Gold and copper were implanted to fluences of 5 to 20 × 1016/cm2 at an energy of 2.0 MeV. Tin was implanted to a fluence of 1.6 × 1017/cm2 at 160 kV. After heat treatment at 1000°C a strong optical absorption peak for the Au implanted samples appeared at ∼620 nm. The absorption peaks of the Ag implanted samples shifted from ∼450 nm before heat treatment to 550 nm after 500°C for lh. Heat treatment at 800°C returned the Ag implanted crystals to a clear state. Cu nanocluster absorption peaks disappears at 500°C. No Sn clusters were observed by optical absorption or XRD. The size of the Ag and Au clusters as a function of heat treatment were determined from the absorption peaks. The Ag clusters did not appreciably change in size with heat treatment. The Au clusters increased from 3 to 9 nm in diameter upon heat treatment at 1000°C. TEM analysis performed on a Au implanted crystal indicated the formation of Au nanocrystals with facets normal to the c-axis. Measurements of the nonlinear refractive indices made using the Z-scan method showed that Ag implantation changed the sign of the nonlinear index of LiNbO3 from negative to positive.

Mechanisms of Formation of Nonlinear Optical Light Guide Structures in Metal Cluster Composites Produced by Ion Beam Implantation

ABSTRACTWe report the results of characterization of linear and nonlinear optical properties of a light guide structure produced by MeV Ag ion implantation of LiNbO3 crystal (z-cut) in relation to the mechanisms of formation.

Linear and Nonlinear Optical Properties of Metal Nanocluster-Silica Composites Formed by Sequential Implantation of Ag And Cu

AbstractMetal nanocluster-glass composites demonstrate unique optical properties and significant nonlinear response. In this work nanometer dimension metal colloids were formed in silica by sequential implantation of Ag and Cu ions. The Ag and Cu were implanted with relative ratios of Ag to Cu of 9:3,6:6, and 3:9 at a total nominal dose of 12xl016 ions/cm2. TEM techniques were used to examine colloid size and size distributions. The linear optical response was measured from 200 to 900 nm, while the nonlinear optical properties were measured using the z-scan technique at a wavelength of 570 nm. The linear and nonlinear optical properties were found to be dependent upon the ratio of sequentially implanted Ag to Cu and are consistent with effective medium theory.

Intense blue-emission band and the fabrication of blue light emitting diodes in I-doped and Ag-ion-implanted cubic ZnS

The nature of the blue-emission bands appearing in highly conductive n-type and Ag-ion-implanted cubic ZnS with iodine (ZnS:1) has been investigated by means of time-resolved photoluminescence and electroluminescence measurements. It is found that the n-type crystal exhibits extremely efficient blue luminescence around 2.65 eV and involves two kinds of donor-acceptor pair transition in it. The Ag-ion-implanted crystal produces also the intense blue band at about 3.0 eV due to the electronic transition from the conduction band to the Ag acceptor level located at 0.6 eV above the valence band. A forward-biased electroluminescent diode capable of emitting bright blue emission bands at 2.9 and 2.7 eV, at room temperature, has been reproducibly prepared using Ag-ion implantation and subsequent recoil implantation techniques, and yields an external quantum efficiency of about 5 \times 10^{-4} percent. The results obtained can be compared with those in a Schottky-barrier diode (having a quantum efficiency of about 10-2percent) made of Au electrode/n-ZnS:I crystal with cleaved

The ion implantation of ZnS

The properties of ZnS single crystals doped by the Ag ion implantation (an acceptor) and zinc (a donor) were investigated. The annealing of the Ag doped samples in H 2 resulted in an occurrence of the “silver” luminescence centres with the photoluminescence maximum at 454 nm. The doped layer depth is ∼500Å at the ion energy of 45 keV. At the annealing of the samples in the S and ZnS vapours the doped layer acquires the p-type conductivity. The doping of n-type ZnS crystals by Zn ions increases their conductivity. At the smooth decrease in the ion beam energy the “ohmic” contact is obtained on the samples.