Chemieal Bonding States of TiC Films before and after Hydrogen Ion Irradiation

TiC films deposited by rf magnetron sputtering followed by Ar＋ ion bombardment were irradiated with a hydrogen ion beam. X-ray photoelectron spectroscopy （XPS） was used for characterization of the chemical bonding states of C and Ti elements of the TiC films before and after hydrogen ion irradiation, in order to understand the effect of hydrogen ion irradiation on the films and to study the mechanism of hydrogen resistance of TiC films. Conclusions can be drawn that ion bombardment at moderate energy can cause preferential physical sputtering of carbon atoms from the surface of low atomic number （Z） material. This means that ion beam bombardment leads to the formation of a non-stoichiometric composition of TiC on the surface. TiC films prepared by ion beam mixing have the more excellent characteristic of hydrogen resistance. One important cause, in addition tO TiC itself, is that there are many vacant sites in TiC created by ion beam mixing. These defects can easily trap hydrogen and effectively enhance the effect of hydrogen resistance.     

氧在阻氢薄膜TiC_x中的行为研究

采用磁控溅射和离子束混合技术制备不同C/Ti含量比的TiCx阻氢薄膜,并利用XPS测试手段分析氧在薄膜中的分布及存在方式,进而分析C/Ti含量比和H＋辐照对氧行为的影响,以期求得在不影响TiCx薄膜阻氢性能的基础上有效降低薄膜中氧含量的途径,提高薄膜的抗氧化性能,延长薄膜的有效寿命。     

脉冲多弧离子镀沉积类金刚石薄膜的牢固度研究

利用脉冲多弧离子镀技术在硅基片上沉积类金刚石薄膜．分析了类金刚石薄膜的牢固度与各种工艺条件的关系．实验结果表明：基片的清洗、基片温度、主回路电压、脉冲频率、烘烤处理都强烈影响类金刚石薄膜的牢固度．同时从理论上分析了利用离子束辅助蒸发工艺可以进一步提高类金刚石薄膜的牢固度     

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).     

大尺寸碳化硅基空间反射镜制备工艺及性能

采用轻量化的硅/碳化硅复合材料制造大尺寸摆镜或高分辨率相机的主镜.该材料的组织构成是双峰分布的碳化硅晶粒和游离硅.利用碳化硅、碳注浆成型制备复杂轻量化结构的的素坯.在硅气相渗透过程中,碳与硅反应形成新的碳化硅,过量硅填充坯体孔隙.由于干燥和反应过程中收缩量小,可用来制备形状复杂且无缺陷的大尺寸样品.硅/碳化硅复合材料可用作空间光学镜面基板,利用电子束物理气相沉积,在基板上沉积硅膜,同时检测硅/碳化硅复合材料和硅膜的性能.制备了各种尺寸的空间用反射镜,直径为120 mm的六角形镜面重0.23 kg,厚度15 mm,表面抛光并镀硅膜,后开式蜂窝状结构的面密度为24.3 kg/m2,面形精度为0.1λ@632.8 nm p-v,表面粗糙度<3nm rms.利用有限元分析方法估计实际条件下的应力和变形.     

Influence of the Plasma State on the Formation of Nano Crystalline SiC Films

The influence ofthe plasma state on the microstructure transformation from amorphousto nanocrystalline state is emphasized during the formation of the silicon carbide (SIC) films deposited by the plasma enhanced chemical vapor technique. The effect of two key parameters, the working pressure and hydrogen concentration in the gas flow, that perform the dependence by modulating the two essential factors of the plasma stateions energy and gas composition, is in-depth investigated. The experimental results showed that nanocrystalline SiC films fit for field emitters could be achieved under an appropriate ion energy flow density and gas components in the plasma.     

Gold Nanoparticulate Thin Films Fabricated by the Electrostatic Self—Assembly Process

Gold colloids were prepared by citrate-induced reduction of hydrogen tetrachlorourate, and gold nanoparticles were electrostatically self-assembled with poly (diallyldimethylammonium chloride) into multilayer thin films on silicon and quartz substrates. The particulate thin films were characterized by UV-vis spectroscopy, surface enhanced Raman scattering, atomic force microscopy and resistivity measurements. Due to the interparticle coupling between individual gold particles, an obvious collective particle plasmon resonance was observed on UV-vis spectra, and the particulate thin films exhibited a strong SERS effect. For multilayer thin films with a high particle coverage on substrates, resistivity of the order of 10⁻⁴Ω·cm was yielded. Yu Hai-hu This research was financially supported by China Scholarship Council and the Natural Science Foundation of Hubei Province (Project 2000J002)     

离子轰击辅助电子束蒸发制备含有纳米石墨结构的非晶碳膜

采用离子轰击辅助电子束蒸发技术制备了含有纳米石墨结构的碳膜。利用XRD、Ralnan和AFM等方法分析了碳膜的厚度、结构、相成分和形貌。结果表明制备的碳膜是一种具有纳米石墨结构的非晶碳膜。随着离子轰击能量的增大,碳膜的厚度随之减小,纳米石墨结构sp2团簇的尺寸变大,碳膜表面粗糙度增大,并找到了最佳的离子轰击能量。通过对Raman光谱分析发现,在最佳离子轰击能量下形成的纳米石墨结构sp2团簇尺寸大小约为2nm。     

Improved oxidation resistance of chemical vapor reaction SiC coating modified with silica for carbon/carbon composites

To protect carbon/carbon (C/C) composites from oxidation, a SiC coating modified with SiO2 was prepared by a complex technology. The inner SiC coating with thickness varying from 150 to 300 μm was initially coated by chemical vapor reaction (CVR): a simple and cheap technique to prepare the SiC coating via siliconizing the substrate that was exposed to the mixed vapor (Si and SiO2) at high temperatures (1 923?2 273 K). Then the as-prepared coating was processed by a dipping and drying procedure with tetraet...     

High temperature cyclic oxidation behavior of Y2O3-ZrO2 thermal barrier coatings irradiated by high-intensity pulsed ion beam

The high-temperature oxidation resistance behavior of 7% (mass fraction) Y₂O₃-ZrO₂ thermal barrier coatings (TBCs) irradiated by high-intensity pulsed ion beam (HIPIB) was investigated under the cyclic oxidation condition of 1 050 °C and 1 h. The columnar grains in the TBCs disappear after the HIPIB irradiation at ion current densities of 100–200 A/cm² and the irradiated surface becomes smooth and densified after remelting and ablation due to the HIPIB irradiation. The thermally grown oxide (TGO) layer thickness of the irradiated TBCs is smaller than that of the original TBCs. After 15 cycles, the mass gains of the original TBCs and those irradiated by ion current densities of 100 and 200 A/cm² due to the oxidation are found to be 0.8–0.9, 0.6–0.7, and 0.3–0.4 mg/cm², respectively. The inward diffusion of oxygen through the irradiated TBCs is significantly impeded by the densified top layer formed due to irradiation, which is the main reason for the improved overall oxidation resistance of the irradiated TBCs. Foundation item: Projects supported by The 2nd Stage of Brain Korea and Korea Research Foundation     

Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> thin films prepared by sulfurizing different multilayer metal precursors

Cu₂ZnSnS₄ (CZTS) thin films were successfully fabricated on glass substrates by sulfurizing Cu-Sn-Zn multilayer precursors, which were deposited by ion beam sputtering and RF magnetron sputtering, respectively. The structural, electrical and optical properties of the prepared films under various processing conditions were investigated in detail. Results showed that the as-deposited CZTS thin films with the precursors by both ion beam sputtering and RF magnetron sputtering have a composition near stoichiometric. The crystallization of the samples, however, has a strong dependence on the atomic percent of constituents of the prepared CZTS films. A single phase stannite-type structure CZTS with a large absorption coefficient of 10₄/cm in the visible range could be obtained after sulfurization at 520°C for 2 h. The samples relative to the RF magnetron sputtering showed a low resistivity of 0.073 Ωcm and band gap energy of about 1.53 eV. The samples relative to the ion beam sputtering exhibited a resistivity of 0.36 Ωcm and the band gap energy is about 1.51 eV. Supported by the National Natural Science Foundation of China (Grant No. 10574106), the Planned Science and Technology Project of Guangdong Province (Grant No.2003C05005) and the Natural Science Fund of Zhanjiang Normal University (Grant No.200801)     

辅助气体对分阶段制备金刚石膜的影响

采用形核 甲烷/氢气生长-辅助气体/甲烷/氢气生长的新工艺,在镜面抛光的单晶硅片上制备了金刚石膜,并用扫描电子显微镜和激光拉曼光谱等测试方法对薄膜的表面形貌和质量性能进行了表征;研究了添加辅助气体对已有金刚石晶型生长的影响.结果表明:以甲烷/氢气为气源时,金刚石膜生长率一般为1.8 μm/h,当分别加入氧气、二氧化碳、氮气时,其生长率都有所提高,其中加入二氧化碳时,其生长率是甲烷/氢气为气源的3倍多,但是加入氩气时,其生长率下降;通过新工艺,在加入氮气或氩气时,第一生长阶段为微米,而第二生长阶段为纳米尺寸,最后制备出具有微/纳米双层复合金刚石膜.     

Thickness dependence of the initial oxidation behaviors of Gd films grown on Si by laser molecular beam epitaxy

Gd thin films with different thickness(about 10 nm and 0.5 nm)were deposited on Si(100)by laser molecular beam epitaxy(LMBE).Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy(XPS)and ultraviolet photoelectron spectroscopy(UPS)analysis under ultra-high vacuum(UHV)condition.When the thin film is around 10 nm,the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic.The UPS results show that the Gd 4f has a double-peak structure and the double-peak structure of Gd 4f evolves into a single-peak feature after exposing to air.When the thickness of the Gd film decreases to about 0.5 nm,the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results.It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier,which block the further diffusion of oxygen and water vapor into the Gd layers.     

Optical properties and microstructure of Ta<Subscript>2</Subscript>O<Subscript>5</Subscript> thin films prepared by ion assisted electron beam evaporation

An effective method for determining the refractive index of weak absorption transparent thin films was presented, which is also applicable to other weak absorption dielectric thin films. The as-deposited Ta2O5 thin films prepared by ion assisted electron beam evaporation showed a maxima transmittance as high as 93% which was close to that of the bare substrate, and exhibited a blue shift when the substrate temperature increased from room temperature to 250 ℃. The refractive index seemed to be immune to the substrate temperature and film thickness with its value about 2.14 at incidence wavelength of 55（1 nm. The surface morphology measured by atomic force microscopy （AFM） revealed that the microstructures lead to the slim optical difference, which was the interplay of substrate temperature and assisted ion beam.     

Impedance Spectroscopy of Ion Beam Mixed Cu/BaTiO_3PTCR Ceramics

The positive temperature coefficient resistance ( PTCR) barium titanate ceramic samples have been prepared by the standard solid-state reaction method, and the ceramic samples have been treated by depositing copper films with magnetron sputtering method. The metallic copper films deposited on the ceramic substrates have been mixed at room temperature with argon ions in energy of 400 keV. Ion beam mixing induced modification of PTCR behavior of the ceramics was studied by using the ac complex impedance method and the resistance vs. temperature measurements . The results showed that room temperature resistance dramatically decreased and Curie point shifted toward higher temperature side for the ion beam mixed samples.     

Impedance Spectroscopy of Ion Beam Mixed Cu／BaTiO3 PTCR Ceramics

The positive temperature coefficient resistance (PTCR) bariumtitanate ceramic samples have been prepared by the standard solid-state reaction method, and the ceramic samples have been treated by depositing copper films with magnetron sputtering method. The metallic copper films deposited on the ceramic substrates have been mixed at room temperature with argon ions in energy of 400 keV. Ion beam mixing induced modification of PTCR behavior of the ceramics was studied by using the ac complex impedance method and the resistance vs. temperature measurements. The results showed that room temperature resistance dramatically decreased and Curie point shifted toward higher temperature side for the ion beam mixed samples.     

Field Emission Properties of Nano-DLC Films Prepared on Cu Substrates by Pulsed Laser Deposition

Nano-diamond like carbon (DLC) thin films were prepared on fused silica and Cu substrates by the pulsed-laser deposition technique with different laser intensities. Step-measurement, atomic force microscope (AFM), UV-VIS-NIR transmittance spectroscopy and Raman spectroscopy were used to characterize the films. It was shown that the deposition rate increases with the laser intensity, and the films prepared under different laser intensities show different transparency. Raman measurement showed that the content of sp³ of the Nano-DLC thin films decreases with the laser intensity. The field emission properties of the Nano-DLC thin films on Cu substrates were studied by the conventional diode method, which showed that the turn-on field increases and the current density decreases with sp³ content in the films. A lower turn-on field of 6 V/um and a higher current density of 1 uA/cm² were obtained for Nano-DLC thin films on Cu substrate.     

离子束辅助沉积非晶硅薄膜红外光学特性研究

为了得到非晶硅（a-Si）薄膜红外光学常数与工艺参数之间的关系,采用Ar离子束辅助电子束热蒸发技术制备a-Si薄膜,并利用椭偏仪和分光光度计测量了薄膜的光学常数,分析了薄膜沉积速率、基底温度和工作真空度对a-Si薄膜折射率和消光系数的影响.实验结果表明：影响a-Si薄膜光学常数的主要工艺因素是沉积速率和基底温度,工作真空度的影响最小.当沉积速率和基底温度升高时,薄膜的折射率先增大后减小;当工作真空度升高时,薄膜的折射率增大.在波长1~5μm之间,a-Si薄膜的折射率变化范围为2.47~3.28.     

星形微波等离子体化学气相沉积装置上类金刚石薄膜的制备

以甲烷、氢气和氧气为反应气体,分别在镜面抛光的单晶硅片和石英玻璃基片上制备了类金刚石薄膜,并用扫描电子显微镜、激光拉曼光谱和傅立叶红外透射光谱仪等测试方法对薄膜的表面形貌、质量和光学性能进行了表征;通过对类金刚石（DLC）薄膜制备过程中碳源浓度、基片温度等参数的研究,掌握了工艺参数对薄膜性能的影响规律,并在此基础上成功地对薄膜的沉积工艺进行了优化.结果表明,当反应气体中的流量配比为甲烷∶氢气∶氧气=10∶100∶1,腔体压力和基片温度分别为0.5 kPa和400℃,制备出的DLC薄膜表面光滑平整,薄膜中的纳米金刚石特征峰明显,在石英玻璃上沉积的DLC薄膜在3 000～4 000 cm-1波数区间透光率超过80％,达到了光学应用要求.     

Property improvement of multilayer TiN/Ti films with C+ implantation

Using the MEVVA ion source, carbon ions have been implanted in TiN coatings deposited by multiarc ion plating. The Vickers microhardness of the C⁺-implanted TiN films increased with the increase in the ion flux and dose. X-ray diffraction (XRD) analysis showed that the TiC phases had been formed in the films. In addition, the films had the preferred growth orientations of TiN and TiC, both of which were (111) orientation after annealing at 500°C for 30 min. Auger electron spectra analysis indicated that C⁺-implanted profile was in typical Gaussian-like distribution in single films. The distribution with multipeaks of C atoms was obtained in multi-layer TiN/Ti. The possibility of the multilayer films (Ti(C,N)/TiN/Ti(C,N)/TiN and Ti(C,N)/TiC/Ti(C,N)/TiC) forming using the C-implanted TiN/Ti films is presented for the first time. Project supported by the National Natural Science Foundation of China and the “863” Hi-Tech Program of China.