Determination of mechanical properties of pulsed laser-deposited hydroxyapatite thin film implanted at high energy with N+ and Ar+ ions, using nanoindentation

Hydroxyapatite (HA) is extensively studied for various applications in bone implantology. We report here a comparison between the effects of ion beam implantation treatment using nitrogen and argon ions, on the mechanical characteristics of HA films grown by pulsed laser deposition. We used for deposition a KrF* excimer laser. Crystalline and stoichiometric HA films were grown on Ti-5Al-2.5Fe alloy substrate, previously coated with a TiN buffer layer. After deposition, the film were implanted with ions of N⁺ and Ar⁺ of high energy (1–1.5 MeV range) and dose set at 10¹⁶ at cm^–2. The hardness and elastic modulus were determined by nanoindentation tests using a spherical tipped nanoindenter with a 5 m-tip radius. From the load-displacement curves, we put into evidence an enhancement of the mechanical characteristics of the HA films after implantation, especially for those implanted with N⁺ ions. This improvement of the mechanical characteristics is related to the changes of surface morphology and the densification of the HA layer after ion treatment.     

Ellipsometric studies of N implanted Ti thin films

Spectroscopic ellipsometry was employed to study the optical response of N⁺ irradiated titanium thin films synthesized by pulsed laser deposition technique. The ellipsometric parameters were measured in the energy range of 1.5 to 5.5 eV. A combined Drude Lorentz (DL) model was employed to quantitatively describe the behavior of the dielectric response as a function of N⁺ irradiation fluence. A modeling based on effective medium approximation (EMA) was carried out to compute the volume fractions of Ti and TiN from the dielectric response functions. The plasma energy as computed from the DL model, decreased with increasing fluence. The results are explained on the basis of formation of TiN phase which was revealed from grazing incidence X-ray diffraction studies. This was further corroborated from the alterations on volume fraction of titanium as inferred from EMA based computation.     

Nonlinear distribution model of ions implanted at high doses

A nonlinear distribution model of ions implanted at high doses is developed with allowance for sputtering, volume growth of a target, and retardation by interstitial atoms. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 2, pp. 277–281, March–April, 1998.     

Wear resistance of TiN coatings implanted with Al and N ions

Titanium nitride (TiN) coatings were prepared on HS 6-5-2 high-speed steel cutting inserts and next implanted either with Al ions (fluence 2×10¹⁷ ions/cm²) or with Al and N ions (fluence (1+1)×10¹⁷ ions/cm²) on the rake face. Microhardness and friction coefficient of the implanted surfaces were examined. A noticeable increase of microhardness in Al implanted inserts has been observed.The elemental composition and structural properties of the surface layer were examined by glow discharge optical emission spectroscopy (GDOES) and gliding angle X-ray diffraction (XRD).The tests of turning of 40 H constructional steel with the cutting inserts have shown an improvement in the implanted inserts, especially marked in those implanted with Al+N.     

Structural studies of reactive pulsed laser-deposited CNx films by X-ray photoelectron spectroscopy and infrared absorption

The changes in the structure of reactive pulsed laser-deposited (RPLD) CN_x films with nitrogen content from 3.6–22 at% have been investigated by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Fourier transform–infrared (FT–IR) absorption. The films were found to be amorphous, and to consist of a network of rings. The rings that were composed solely of carbon atoms gave rise to an XPS peak located between 284.3 and 284.8 eV (C¹ component). The rings containing nitrogen led to another peak located between 285.5 and 286.4 eV (C² component). When the nitrogen content increased, the relative intensity of the C¹ component fell, while that of the C2 component rose, indicating that some carbon atoms in the rings were replaced by nitrogen atoms. C≡N bonds also contributed to the C² component. The FT–IR data were consistent with this interpretation. No evidence for the existence of a β-C₃N₄ phase was found in RPLD CN_x films. This revised version was published online in November 2006 with corrections to the Cover Date.     

GHz高磁导率铁磁薄膜研究进展

主要介绍了微波(GHz)频率下,高磁导率铁磁性薄膜近年来的最新研究进展。对于制备在柔性基片上的铁磁薄膜,重点介绍了Fe基、Co基合金薄膜,并分析了各成分对薄膜的影响;纳米晶薄膜的重点集中在Fe—N及FeXN系薄膜上,介绍了各类FeN相在薄膜中所起的作用;对于T—M—O系纳米磁性颗粒膜,分析了磁性颗粒膜的微波高磁导率机理。同时提出了目前探索GHz频率下高磁导率磁性薄膜主要面临的问题。     

Gas-sensor properties of SnO2 films implanted with gold and iron ions

SnO₂ gas-sensor films were modified by implantation of gold and iron ions. The change in electrical resistivity of the films caused by inflammable gases, H₂, CO, CH₄ and C₂H₅OH, was measured in the temperature range 100–500°C, and compared to non-implanted films. The morphological changes caused by gold and iron ion implantation were also investigated by atomic force microscopy. After ion implantation and annealing at 600°C, the sensitivity to H₂ and CO gas was found to increase, and the dynamic range of the sensitivity to ethanol was improved. The sensitivity to CH₄ was low before and after ion implantation. Fe₂O₃ (3%SnO₂) film was also modified by gold ion implantation for comparison. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fatigue-less relaxor ferroelectric thin films with high energy storage density via defect engineer

Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3-x％Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density～47.6 J cm-3 and good efficiency～65.68％are simultaneously achieved in 2％Mn doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor.Moreover,the 2％Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35-115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2％Mn-doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.     

Recording properties of thin magnetic films at high densities

A set of recording measurements obtained from a series of cobalt-phosphorus thin film rigid discs is presented. Directly measured roll-off curves are compared with those obtained by linear superposition of both experimental and analytic isolated pulses. Nonlinear behavior at high densities is observed     

A parametric study of AlN thin films grown by pulsed laser deposition

High quality AlN thin films were grown at 200–450°C on sapphire substrates by laser ablation of Al targets in nitrogen reactive atmosphere. The nitrogen pressure was varied between 10⁻³ and 10⁻¹ mbar. The reactive gas pressure during irradiation and the temperature of the substrate were found to essentially influence the quality of the layers. X-ray diffraction analysis evidenced the formation of highly orientated layers for a very restrictive set of parameters. Other analysis techniques, like X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, optical transmission spectroscopy have been used to evidence the good stoichiometry and purity of the films. The characteristics of these films were compared with those of AlN thin films deposited in similar experimental conditions, on Si (100) and Si (111) substrates.     

Atomic layer deposition and characterization of biocompatible hydroxyapatite thin films

Atomic layer deposition (ALD) was used to produce hydroxyapatite from Ca(thd)₂ (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) and (CH₃O)₃PO onto Si(100) and Corning (0211). Film crystallinity, stoichiometry, possible impurities and surface morphology were determined. The as-deposited films contained significant amounts of carbonate impurities however, annealing at moist N₂ flow reduced the carbonate content even at 400 °C. The as-deposited Ca-P-O films were amorphous but rapid thermal annealing promoted the formation of the hydroxyapatite phase. Mouse MC 3T3-E1 cells were used for the cell culture experiments. According to the bioactivity studies cell proliferation was enhanced on as-deposited ALD-grown Ca-P-O films and greatly enhanced on films annealed at 500 °C in comparison with reference cells on borosilicate glass or cell culture polystyrene.     

Reactive deposition of aluminium-doped zinc oxide thin films using high power pulsed magnetron sputtering

High power pulsed magnetron sputtering has been used for depositing Al-doped ZnO films from metallic targets in a reactive process. A new type of process control has been developed in order to stabilize the discharge in the transition region. It has been shown that the process can be stabilized for all operating points at high peak power densities. The discharge characteristics like peak power density and plasma impedance have been analyzed. Films have been deposited at room temperature and 200 °C and resistivities below 400 μΩcm have been obtained.     

Sputter deposition of ZnO thin films at high substrate temperatures

ZnO thin films have been deposited on GaN and ZnO substrates at substrate temperatures up to 750 °C by radio-frequency sputtering using ZnO ceramic targets in pure argon or in a mixture of argon and oxygen. By optimizing the sputter parameters, such as sputtering power, Ar/O₂ sputtering gas ratio and temperature of the substrates high quality films were obtained as judged from the X-ray rocking curve half width and luminescence line width. The crystallinity of the ZnO films increases with increasing substrate temperature. Yet there are distinct differences between films grown on GaN templates and on O- and Zn-polar ZnO substrates.     

Effect of implanted phosphorus ions on the crystallization of amorphous silicon films under the action of pulsed excimer laser radiation

We have studied the effect of implanted phosphorus ions on the crystallization of thin amorphous silicon films under the action of nanosecond radiation pulses of a XeCl excimer laser. The amorphous silicon films with a thickness of 90 nm, obtained by plasmachemical deposition on glass substrates, were implanted with phosphorus ions at a dose of 3 × 10¹⁴ and 3 × 10¹⁵ cm⁻². The subsequent laser treatments were performed using energies both above and below a threshold corresponding to the fusion of amorphous silicon. The structure of the silicon films was studied using Raman scattering spectroscopy. An analysis of the experimental data shows that implanted phosphorus stimulates nucleation, especially in the case of liquid phase crystallization. The results are of interest for the development of the technology of thin-film transistors on nonrefractory substrates.     

Properties of aluminium oxide thin films deposited in high effective reactive pulsed magnetron sputtering process

Pulsed magnetron sputtering of metal targets in the presence of reactive gas is widely used to deposit compound materials. This method is very popular but still the aim of research is to obtain more stable and efficient processes. The standard procedure of compound thin film deposition is sputtering in so called reactive mode of magnetron work ?? sputtering of the target surface covered with the formed compound. The authors postulate that the problem of low deposition rate of reactive compounds can be solved if the magnetron source operates in the metallic mode or near the border of metallic and transient mode. Aluminium oxide thin films were deposited using high effective reactive pulsed magnetron sputtering. The main purpose of the research was electrical characterization of metal-compound-metal structures in the wide range of frequencies and determination of deposition technique influence on the thin film properties.     

Analysis of coatings and thin films using energetic ions

Energetic ion analysis techniques provide non-destructive information on the depth distribution of atomic composition in the near-surface (1–10 μm) region of a solid sample. The techniques are quantitative and are not complicated by the presence of chemical or matrix effects. Generalized nuclear reaction analysis is described and its application to the measurement of the stoichiometry of Ta₂O₅ films and BeO coatings on Cu-Be is briefly discussed.     

Reactive pulsed laser deposition of thin molybdenum- and tungsten-nitride films

In this work reactive pulsed laser deposition of molybdenum- and tungsten-nitride thin films is investigated. Metallic targets were ablated in low-pressure (1, 10 and 100 Pa) nitrogen atmosphere by KrF excimer laser pulses (fluence ∼6.5 J/cm²). Films were deposited on silicon wafers heated to ∼25, 250 and 500 °C. The characteristics of the films strongly depend on the N₂ pressure. By increasing N₂ pressure, the nitrogen content increases in the films, which leads to a monotonous increase of the electrical resistivity. Deposition rate decreases at 100 Pa as indicated by Rutherford backscattering spectrometry. At this pressure, hardness of the films significantly decreases also, as shown by microhardness measurements. X-ray diffractometry shows that films crystallinity is improved by increasing the substrate temperature. In addition, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were applied for visualising the film surface.