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 un-derstant 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 evo     

The corrosion behavior of nano-meter embedded phase in Ti implanted H13 steel

On the SEM micrographs of Ti implanted H13 steel, a tree-branch-like structure can be observed. Further investigation with TEM shows that the newly tormed composition is a formation of nann-meter FeTi_2 phase in Ti implanted layer. The layer with a relatively high corrosion resistance has been formed in Ti implanted H13 steel with this structure.The results of electrochemical measurement show that the corrosion current density decreases obviously with an increase of ion dose. The corrosion current density in Ti implanted steel with a dose of 1.3×10~(18)/cm~2 is 8-20 times less than that of Ti implanted steel with a dose of 6×10~(17)/cm~2. The corrosion behavior of Ti implanted steel with a dose of 6×10~(17)/cm~2 could be further improved as the sample was annealed at 500℃ for 20 min and the corrosion current density decreases by 48-80 times compared to that of non-implanted samples. The corrosion trace was not observed on the annealing sample by SEM, after multi-sweep cyclic voltammetry of 40 cycles     

Nano-phases and corrosion resistance of C+Mo dual implanted steel

The corrosion resistance of C + Mo dual-implanted HI3 steel was studied using multi-sweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation solid station solution of Mo+ and C+ atoms was formed in Mo + C dual implanted steel. Precipitate phase with nanometer size Fe2Mo, FeMo, MoC, Fe5C3 and Fe7C3 were formed in dual implanted layer. The passivation layer consisted of these nanometer phases. The corrosion resistance of the dual implanted layer was better than that of single Mo implantation. Jp of the Mo implanted sample is 0.55 times that of H13 steel. The corrosion resistance of the dual implantation was enhanced when ion dose increased. When the Mo+ ion dose was 6 × 1017/cm2 in the dual implantation, Jp of the dual implanted sample was only 0.11 times that in H13 steel. What is important is that pitting corrosion properties of dual implanted steel were improved obviously.     

Plasma-enhanced Chemical Vapordeposition SiO2 Film after Ion Implantation Induces Quantum Well Intermixing

A method of QWI ( quantum well intermixing) realizing through plasma-enhanced chemical vapordepositiom (PECVD) SiO2 film following ion implantation was investigated. PECVD 200 nm SiO2 film after 160 keV phosphorus(P) ion implantation was performed to induce InP-based multiple-quantum-well (MQW) laser structural intermixing, annealing process was carried out at 780 ℃ for 30 seconds under N2 flue, the blue shift ofphotoluminescence (PL) peak related to implanted dose: 1 × 1011 , 1 × 1012, 1 × 1013 ,3 × 1013 , 7 × 1013 ion/ cm2 is 22 nm, 65 nm, 104 nm, 109 nm, 101 nm, respectively. Under the same conditions, by comparing the blue shift of PL peak with P ion implantation only, slight differentiation between the two methods was observed, and results reveal that the defects in the implanting layers generated by ion implantation are much more than those in SiO2 film. So, the blue shift results mainly from ion implantation. However , SiO2 film also may promote the quantum well intermixing.     

Experimental studies of N~+ implantation into CVD diamond thin films

The effects of N+ implantation under various conditions on CVD diamond films were analyzed with Raman spectroscopy, four-point probe method, X-ray diffraction (XRD), Rutherford backseattering spectroscopy (RBS), ultraviolet photoluminescence spectroscopy (UV-PL), Fourier transformation infrared absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the N+ implantation doping without any graphitization has been successfully realized when 100 keV N+ ions at a dosage of 2 × 1016 cm-2 were implanted into diamond films at 550℃ . UV-PL spectra indicate that the implanted N+ ions formed an electrically inactive deep-level impurity in diamond films. So the sheet resistance of the sample after N+ implantation changed little. Carbon nitride containing C≡N covalent bond has been successfully synthesized by 100 keV, 1.2×1018 N/cm2 N+ implantation into diamond films. Most of the implanted N+ ions formed C≡N covalent bonds with C atoms. The others were free state nitroge     

Influence of Aluminum Ions Implantation on Corrosion Behavior of Zircaloy-2 Alloy in 1M H2SO4

The specimens were implanted with aluminum ions with fluence ranging from 1× 10^16 to 1× 10^17 ions/cm^2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Transmission electron microscopy （TEM） was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-2 in a 1 M H2SO4 solution. It is found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-2 implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum- implanted zircaloy-2 was discussed.     

薄层轻掺杂N-GaAs半导体欧姆接触研究

利用Ni/Ge/Au/Ni/Au和Pd/In两种金属结构成功地对体硅掺杂N-GaAs半导体(Nd=10~(18)cm~(-3))和离子注入N-GaAs半导体(dose=8×10~(12)cm~2,注入有源区深度(d=0.2μm)制成低阻欧姆接触。并对实验结果和接触机理进行了讨论。所得合金接触的接触电阻率分别为10~(-6)Ωcm~2(10~(18)cm~(-3)掺杂),和10~(-3)Ωcm~(-2)(8×10~(12)cm~2注入)数量级并具有长期的稳定性。接触制备方法和GaAs工艺相适。     

Electron Spectroscopy Studies on SiC Films before and after Hydrogen Ion Irradiation

1Introduction Theinteractionbetweenenergetichydrogenandlow Zmaterials,suchasSiC,hasbeenstudiedinseveral groupsbecausecarbidesoflowZelementsareusedfor plasmafacingcomponentsasfirstwallmaterialsin Tokamak[1,2].Hence,itisofinteresttounderstandthe effectsofHp…     

Physical properties of Al-doped ZnO and Ga-doped ZnO thin films prepared by direct current sputtering at room temperature

Al-doped zinc oxide(AZO) and Ga-doped zinc oxide(GZO) thin films with the same doping concentration(3.6 at%) were deposited on glass substrates at room temperature by direct current(DC) magnetron sputtering.Consequently,we comparatively studied the doped thin films on the basis of their structural,morphological,electrical,and optical properties for optoelectronic applications.Both thin films exhibited excellent optical properties with more than 85%transmission in the visible range.The GZO thin film had better crystallinity and smoother surface morphology than the AZO thin film.The conductivity of the GZO thin film was improved compared to that of the AZO thin film:the resistivity decreased from 1.01×10~(-3) to 3.5×10~(-4) Ω cm,which was mostly due to the increase of the carrier concentration from 6.5×10~(20) to 1.46×10~(21)cm~(-3).These results revealed that the GZO thin film had higher quality than the AZO thin film with the same doping concentration for optoelectronic applications.     

Extraordinary self-lubrication properties of non-hydrogenated diamond-like carbon films under humid atmosphere

Tribological properties of non-hydrogenated diamond-like carbon (DLC) films were investigated under humid (RH=80%) and dry (RH=5%) air. These films were deposited by pulsed laser deposition (PLD) at different substrate temperatures. Tribological properties of DLC fabricated by PLD is not sensitive to the relative humidity of testing environment. Because of the unique growth mechanism of DLC prepared by PLD, DLC is of “soft-hard” double layers, having a very low friction coefficient and wear rate under humid atmosphere. The minimum coefficient and wear rate of film under humid circumstance are 0.045 and 5.94×10⁻¹⁰ mm³N⁻¹m⁻¹, respectively, just a little bit more than those under dry condition. The root means square roughness of film is less than 1 nm. The sp³ content of film grown at room temperature (RT) is 72%, and the sp³ content decreases with temperature. Raman spectrum shows that the micro-structure is amorphous network. The largest hardness and elastic modulus of film are 51 GPa and 350 GPa, respectively and they reduce with increase of deposition temperature too. Water contact angles on surface are more than 90° which indicates that films fabricated by PLD are hydrophobic with low surface energy.     

The effect of the boron-ions implantation on the performance of RADFETs

In this work, we studied on the boron-ions implantation, including the implant dose and post-annealing temperature on the performance of PMOS radiation field-effect transistors(RADFETs) in experimental. The possible traps and defects induced by ions implantation in the gate-oxide and their further impacting on the sensitivity and dose range of RADFETs were analyzed qualitatively. Our devices had the dry/wet/dry sandwich gate-oxide of 420 nm thick. Different ion-implanting doses and post-annealing temperatures were carried out during the RADFETs fabrication. We built a real time auto-measurement system to realize the auto-state-switch between irradiation and read-out modes, and in-situ measurement of output voltage for ten devices in turn at once of radiation experiment. The threshold voltage, dose range and sensitivity of RADFETs were extracted and analyzed in detail. The results showed that the highest sensitivity of 229 mV/Gy achieved when the implant dose was2.2×1011 cm.2 and the post-annealing temperature was 1000°C, and the dose range of 34 Gy as well.     

Effects of h-BN content on properties of Ni-Cr/h-BN composite

Ni-Cr/h-BN self-lubricating composities were prepared by powder metallurgy (P/M) method. The effects of hexagonal boron nitride (h-BN) content on the mechanical and tribological properties of the Ni-Cr/h-BN composites were investigated. The corresponding frictional models were established to analyze the formation of the lubricant h-BN films on the surfaces of the Ni-Cr/h-BN composites. The results show that, when the content of h-BN increases from 5% to 15% (mass fraction), the bending strength of the Ni-Cr/h-BN composite decreases from 96.670 MPa to 17.319 MPa, and the hardness (HB) decreases from 33 to 14. The friction coefficient of the Ni-Cr/h-BN composite decreases firstly from 0.385 to 0.216, and then increases to 0.284, while the wear rate decreases firstly from 4.14×10⁻⁹ kg/(N·m) to 1.35×10⁻⁹ kg/(N·m), then increases to 2.36×10⁻⁹ kg/(N·m). The best comprehensive mechanical and tribological properties can be obtained between 10% and 12% h-BN addition.     

Microstructures and mechanical,electrical, high-temperature properties of Cu/Ti<Subscript>2</Subscript>AlC FGM fabricated by hot-pressing

The microstructure and the electrical, thermal, friction, and mechanical properties of Cu/Ti₂AlC fabricated by hot-pressing at 900 °C for 1 h were investigated in the present work. Microstructural observations have shown that the plate-like Ti₂AlC grains distribute irregularly in the network of Cu grains, and well-structured, crack-free bonds between the layers. With the increase in the content of Ti₂AlC from layer A to layer D, the electrical resistivity increases from 1.381×10^-7 Ω·m to 1.918 ×10^-7 Ω·m, the hardness increases from about 980.27 MPa to about 2196.01 MPa, and the friction coefficient from above 0.20 reduces to about 0.15. Oxidation rate increases with the increases of temperature. Exfoliation was obviously observed on the surface of oxidation layer A. The surface of layer D was still intact and the spalling and other defects were not found. The mass decreases in the acid solution, and increases in the alkaline solution. The largest corrosion rate is found in 6.5% HNO₃ or 4% NaOH solution.     

The hardness of amorphous Si-DLC films by molecular dynamics simulations

Silicon-doped diamond-like carbon (Si-DLC) films possess the potential to improve wear performance of DLC films in humid atmospheres and at higher temperatures. But many experimental results of Si-DLC films show that their structure and mechanical properties have changed greatly with the increasing silicon content. Therefore, molecular dynamics (MD) simulations were used to generate hydrogen-free Si-DLC films and study their nano-indentation process under the interaction of a diamond indenter. The results show that sp ³/sp ²(C) (only carbon atoms) always decreases with the increasing silicon content. But sp ³/sp ²(C+Si) ratio increases firstly and reaches a maximum at the silicon content of 0.2, and then decreases with the further increase of the silicon content. Bulk modulus and hardness of the Si-DLC films both decrease with the increasing of the silicon content, which has the same trend with Papakonstantinou and Ikeyama’s results. It is concluded that the hardness of the Si-DLC films is dependent on sp ³/sp ²(C), not sp ³/sp ²(C+Si).     

Effect of Annealing on Ferroelectric Properties of Bi3.25La0.75Ti3O12 Thin Films Prepared by the Sol-gel Method

Bi_3.25La_0.75Ti₃O₁₂(BLT) thin films were prepared on Pt/Ti/SiO₂/Si substrate by the sol-gel method. The effect of annealing on their structures and ferroelectric properties was investigated. The XRD patterns indicate that the BLT films annealed at different temperatures are randomly orientated and the single perovskite phase is obtained at 550°C. The remnant polarization increases and the coercive field decreases with the annealing temperature increasing. The leakage current density of the BLT films annealed at 700°C is about 5.8×10⁻⁸ Al cm² at the electric field of 250 kV/cm. Funded by the National Natural Science Foundation of China (No. 90407023)     

Growth and characterization of indium doped zinc oxide films sputtered from powder targets

Indium doped Zn O films were grown on quartz glass substrates by radio frequency magnetron sputtering from powder targets. Indium content in the targets varied from 1at% to 9at%. In doping on the structure, optical and electrical properties of Zn O thin films were studied. X-ray diffraction shows that all the films are hexagonal wurtzite with c-axis perpendicular to the substrates. There is a positive strain in the films and it increases with indium content. All the films show a high transmittance of 86% in the visible light region. Undoped Zn O thin film exhibits a high transmittance in the near infrared region. The transmittance of indium doped Zn O thin films decreases sharply in the near infrared region, and a cut-off wavelength can be found. The lowest resistivity of 4.3×10~(-4) Ω·cm and the highest carrier concentration of 1.86×10~(21) cm~(-3) can be obtained from Zn O thin films with an indium content of 5at% in the target.     

Solid State Reaction Synthesis and Thermoelectric Properties of Mg2Si doped with Sb and Te

Doped with Sb and Te, Mg₂ Si based compounds were prepared respectively by solid state reaction at 823K for 8h. Effects of dopants of Sb and Te on the structure and thermoelectric properties of the compounds were investigated. By calculating the values of the electrical conductivity for Sb-doped sample, the mechanism of electric conduction at 625 K is different. The figure of merit for sample doped with 0.4wt% Te at 500K is 2.4×10⁻³W/mK², and it reaches 3.3×10⁻³ W/mK² at 650K for the sample doped with 0.5wt% Sb. The values are more than 1.4 times and 2.3 times of the pure Mg₂Si sample. JIANG Hong-yi : Born in 1961     

Surface wear resistance properties of Ta＋N implanted W18Cr4V high speed steel

High-speed steel W18Cr4V is commonly used in industries such as blade and mould manufacturers because of its high level of hardness and toughness, red-hardness and resistance. Ion implantation is an effective method to improve the wear resis-tance of W18Cr4V. In our investigation, Ta and Ta+N ion implantation was performed on W18Cr4V high-speed steel. The surface properties after implantation were evaluated by measuring friction coefficients while the carbonyl phase of the surface was ana-lyzed by X-ray diffraction analysis. It was found that the friction coefficients of the treated samples were much lower. Samples implanted with Ta+N had a lower friction coefficients than samples implanted only with Ta. This can be attributed to the formation of a new chemical compound, Fe7Ta3, on both surfaces. An even harder chemical compound, Fe2N, was formed on both sttrfaces of Ta+N implanted samples.     

Dopamine detection using a patch-clamp system on a planar microeletrode array electrodeposited by polypyrrole/graphene nanocomposites

To achieve a dopamine(DA)response with high sensitivity and high signal-to-noise ratio(S/N)with a patch-clamp system,polypyrrole/graphene(PPy/GR)nanocomposites were steadily electrodeposited by an electrochemical method on a planar microelectrode array(pMEA)fabricated by a standard micromachining process.The electrodeposition process was carried out by chronopotentimetry measurement scanning from 0.1 to 0.8 C/cm2at the current of 2 mA;0.5 C/cm2was found to be optimal.The pMEA modified by PPy/GR at the 0.5 C/cm2exhibits remarkable properties;for instance,the standard deviation(SD)decreases from 8.4614×10-11to 5.62×10 11A,reduced by 33.52%,and the sensitivity increases from 2566.88 to 76114.65μAmMcm-2,29.65 times higher than the bare Pt(platinum).A good linear relationship between the current and DA concentration in the range of 0.30 to 61.71μm was obtained,with a correlation coefficient of 0.997.The sensor is meaningful for neuroscience research and the treatment of neurological diseases.     

Synthesis of 3D ordered macroporous indium tin oxide using polymer colloidal crystal template

Three-dimensional (3D) ordered macroporous indium tin oxide (ITO) is pre- pared using a polymer colloidal crystal template that is formed by self-assembly of the monodisperse poly(methyl methacrylate) (PMMA) microspheres. The morphologies and BET surface area of the macroporous material is examined by scanning electron micro- scope, transmission electron microscopy and N2 adsorption/desorption. Results indicate that the macroporous material has highly ordered arrays of the uniform pores replicated from the PMMA colloidal crystal template when the polymer colloidal crystal template is removed by calcinations at 500℃. The pore diameter (about 450 nm) of macroporous ITO slightly shrank to the PMMA microspheres. The BET surface area and pore volume of the macroporous material are 389 m2·g-1 and 0.36 cm3·g-1, respectively. Moreover, the macroporous ITO, containing 5 mol% Sn and after annealing under vacuum, shows the minimum resistivity of ρ = 8.2×10-3 Ω· cm. The conductive mechanism of macroporous ITO is discussed, and it is believed that the oxygen vacancies are the major factor for excellent electrical properties.