Fe纳米颗粒嵌埋对类金刚石薄膜结构及电学性能的影响

 采用脉冲激光气相沉积方法制备了不同Fe嵌埋浓度的Fe: DLC多层纳米复合薄膜。用X射线光电子能谱仪(XPS)对薄膜的组成成分进行分析。利用透射电子显微镜（TEM）、拉曼光谱、电流-电压曲线研究Fe纳米颗粒嵌埋对薄膜的微观结构及电学性能的影响。XPS和TEM表明,Fe纳米颗粒周期性地均匀地嵌埋在碳薄膜中。拉曼光谱表明薄膜中的C为典型的类金刚石结构,Fe纳米颗粒促进芳香环式结构的形成,薄膜结构的有序度提高。电流 电压曲线表明,Fe纳米颗粒的嵌埋导致薄膜的室温电导率增加。     

Evaluation of carbon films electrodeposited on different substrates from different organic solvents

Diamond-like-carbon (DLC) films have been deposited on Si, aluminum and indium tin oxide-coated glass from several organic solvents with pulse-modulated power. The films are characterized by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. XPS spectra show that the main composition of the films is carbon and Raman spectra show that the films are typical DLC films and a high potential is preferable in the formation of sp ³-structure carbon. Comparing the results from different solvents and different substrates we deduce that the methyl group of the solvents has a critical function in forming the DLC films. However, the formation process and the characters of the films, such as appearance, resistivity and thickness, are mainly determined by the substrate. We may call this deposition a substrate-controlled reaction. Received: 31 May 2000 / Accepted: 9 January 2001 / Published online: 3 April 2001     

电解有机溶液法在Si表面制备类金刚石薄膜及退火对其结构的影响

在对不同有机溶剂分子结构分析的基础上,选取甲醇、DMF(N,N-二甲基甲酰胺)和乙腈溶液为碳源,以脉冲直流电源电解有机溶液的方法在Si片上制得了含氢类金刚石薄膜(DLC薄膜),并研究了退火对薄膜结构的影响.通过X射线光电子能谱(XPS),喇曼(Raman)和红外(IR)光谱对薄膜的结构进行了分析表征.XPS表明薄膜的主要成分为C,喇曼光谱显示所得薄膜为典型DLC薄膜.喇曼和红外光谱还表明,膜中含有大量H并且主要键合于sp³碳处.随着退火的进行薄膜中的H被去除.随温度升高薄膜电阻率的下 关键词： 类金刚石薄膜 退火     

Characterization of doped diamond-like carbon films deposited by hot wire plasma sputtering of graphite

Diamond-like carbon (DLC) films doped with nitrogen and oxygen were deposited on silicon(100) and polytetrafluoroethylene (PTFE) substrates by hot wire plasma sputtering of graphite. The morphology and chemical composition of deposited films has been characterized by scanning electron microscopy, XPS, Auger, FTIR spectroscopy and micro-Raman scattering. Plasmon loss structure accompanying the XPS C 1s peak and electron energy loss spectroscopy (EELS) in reflection mode was used to study the fraction of sp³ bonded C atoms and the density of valence electrons. Raman spectra show two basic C–C bands around 1575 cm^-1 (G line) and 1360 cm^-1 (D line) . Auger depth profiling spectroscopy was used to measure the spatial distributions of C, N and O atoms in the surface layer of DLC films. The fraction of sp³ bonded atoms of about 40% was detected in DLC films by XPS plasmon loss and EELS techniques. Nitrile and iso-nitrile groups observed in FTIR spectra demonstrated the existence of sp bonded carbon in doped DLC films. The typical for DLC films specific density 1.7–1.8 g/cm³ was obtained from EELS and XPS data. PACS 52.77.Dq; 81.65.-b; 82.80.Pv     

Optical and Electrical Properties Evolution of Diamond-Like Carbon Thin Films with Deposition Temperature

Optical and electrical properties of diamond-like carbon （DLC） films deposited by pulsed laser ablation of graphite target at different substrate temperatures are reported. By varying the deposition temperature from 400 to 25℃, the film optical transparency and electrical resistivity increase severely. Most importantly, the transparency and resistivity properties of the DLC films can be tailored to approaching diamond by adjusting the deposition temperature, which is critical to many applications. DLC films deposited at low temperatures show excellent optical transmittance and high resistivity. Over the same temperature regime an increase of the spa bonded C content is observed using visible Raman spectroscopy, which is responsible for the enhanced transparency and resistivity properties.     

Mechanical properties and platelet adhesion behavior of diamond-like carbon films synthesized by pulsed vacuum arc plasma deposition

Diamond-like carbon (DLC) is an attractive biomedical material due to its high inertness and excellent mechanical properties. In this study, DLC films were fabricated on Ti6Al4V and Si(1 0 0) substrates at room temperature by pulsed vacuum arc plasma deposition. By changing the argon flow from 0 to 13 sccm during deposition, the effects of argon flow on the characteristics of the DLC films were systematically examined to correlate to the blood compatibility. The microstructure and mechanical properties of the films were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) surface analysis, a nano-indenter and pin-on-disk tribometer. The blood compatibility of the films was evaluated using in vitro platelet adhesion investigation, and the quantity and morphology of the adherent platelets was investigated employing optical microscopy and scanning electron microscopy.The Raman spectroscopy results showed a decreasing sp³ fraction (an increasing trend in I_D/I_G ratio) with increasing argon flow from 0 to 13 sccm. The sp³:sp² ratio of the films was evaluated from the deconvoluted XPS spectra. We found that the sp³ fraction decreased as the argon flow was increased from 0 to 13 sccm, which is consistent with the results of the Raman spectra. The mechanical properties results confirmed the decreasing sp³ content with increasing argon flow. The Raman D-band to G-band intensity ratio increased and the platelet adhesion behavior became better with higher flow. This implies that the blood compatibility of the DLC films is influenced by the sp³:sp² ratio. DLC films deposited on titanium alloys have high wear resistance, low friction and good adhesion.     

Influence of sulfidation treatment on the structure and tribological properties of nitrogen-doped diamond-like carbon films

The nitrogen-doped diamond-like carbon (DLC) films were deposited on high speed steel (HSS) substrates in the direct current unbalanced magnetron sputtering system. Sulphurized layer was formed on the surface of DLC films by means of liquid sulfidation in the intermixture of urea and thiourea solution in order to improve the tribological properties of DLC films. The influence of sulfidation treatment on the structure and tribological properties of DLC films was investigated in this work. The structure and wear surface morphology of DLC films were analyzed by Raman spectroscopy, XPS and SEM, respectively. It reveals that the treated films are smooth and uniform; and sulfur atoms are bonded chemically. The treated films have broader distribution of Raman spectra in the range of 1000-1800 cm⁻¹ and higher I_D/I_G ratio than the untreated films as a result of the appearance of the crystalline graphite structure after the sulfidation treatment. It is showed that the sp² relative content increase in the treated films from the XPS measurement. The Raman results are consistent with the XPS results. The tribological properties of DLC films were investigated using a ball-on-disk rotating friction and wear tester under dry friction conditions. It is found that the sulfidation concentration plays an important part in the tribological properties of the treated DLC films. The results showed the treated films with low sulfidation concentration have a lower friction coefficient (0.1) than the treated films with high sulfidation concentration (0.26) and the untreated films (0.27) under the same friction testing conditions, which can be attributed to both the presence of sulfur-containing materials and the forming of the mechanical alloyed layer on the wear surface. Adding the dry nitrogen to the sliding surface in the testing system helps the friction coefficient of the treated films with low sulfidation concentration to decrease to 0.04 further in this work. On the basis of the experimental results, it is indicated that the liquid sulfidation technique, which is low-cost, non-polluting and convenience, would be an appropriate method for the surface treatment of DLC films.     

Synthesis of DLC films by PLD from liquid target and dependence of film properties on the synthesis conditions

DLC (Diamond-like carbon films) were prepared by pulsed laser ablation of a liquid target at substrate temperatures from 18 to 600°C using 248 nm KrF excimer laser. The sp³ hybridization state carbon formation was additionally promoted by gaseous H₂O₂ flow through the reaction chamber and substrate excitation by the same laser beam. Deposited DLC films were characterised by Raman scattering spectroscopy and atomic force microscopy (AFM). Comparative AFM and Raman study shows that the increase in the content of sp³ type bonding in DLC is in correlation with the increase of the surface roughness of the samples prepared.     

A New Empirical Model for Estimation of sp^3 Fraction in Diamond-Like Carbon Films

A new empirical model to estimate the content of sp^3 in diamond-like carbon （DLC） films is presented, based on the conventional Raman spectra excited by 488nm or 514nm visible light for different carbons. It is found that bandwidth of the G peak is related to the sp^3 fraction. A wider bandwidth of the G peak shows a higher sp^3 fraction in DLC films.     

193-nm laser ablation of CVD diamond and graphite in vacuum: plume analysis and film properties

The pulsed laser ablation of chemical vapor deposition (CVD) diamond and graphite samples in vacuum has been investigated by the use of an ArF excimer laser operating at 5=193 nm. The composition and propagation of both ablation plumes has been probed via wavelength and spatially and temporally resolved measurements of the plume emission and found to be very similar. Electronically excited C atoms and C⁺ and C²⁺ ions are identified among the ablated material. Plume expansion velocities are estimated from time-gated imaging of specific C and C⁺ emissions. Langmuir probe measurements provide further insight into the propagation of the charged components in both ablation plumes. Diamond-like carbon (DLC) films grown by 193-nm laser ablation of both target materials on Si substrates maintained at room temperature have been investigated by laser Raman spectroscopy (325 nm and 488 nm excitation) and by both optical and scanning electron microscopy, and their field emission characteristics investigated. Again, similarities outweigh the differences, but DLC films grown from ablation of the diamond target appear to show steeper I/V dependencies once above the threshold voltage for field emission.     

Improving the conductivity of diamond-like carbon films with zinc doping and its material properties

Zinc doped diamond-like carbon (DLC) nanocomposite thin films are fabricated by KrF pulsed laser deposition. Carbon targets containing 3.0, 5.0 and 10.0 atomic percentages of zinc are used as the source for the laser system. Investigation of electrical properties by the four-point probe shows that doping zinc into DLC can lower the electrical sheet resistivity. Microstructural analysis by Raman spectroscopy and XPS show a lower sp³ content but a higher SiC content with an increasing amount of zinc incorporation. The increase of SiC leads to an increase in adhesion strength. Surface roughness of the films also increases while the coefficients of friction for the films do not change.     

Surface modification of diamond-like carbon films with perfluorooctyl functionalities and their surface properties

Photolysis of perfluoroazooctane with diamond-like carbon (DLC) films led to the surface modification to introduce perfluorooctyl functional groups, confirmed by means of FT-IR, XPS, Raman and TOF-SIMS measurements. The DLC films modified with fluorine moieties showed reduction of the surface energy evaluated by contact angle to water, as compared with pristine DLC film. The contact angle of chemically modified DLC film is 105°, comparable to that of polytetrafluoroethylene (PTFE). By monitoring with XPS, we found that the results on the value of fluorine/carbon ratio of fluorinated DLC films depending on irradiation time are consistent with those of contact angle. Chemical modification of DLC films with perfluorooctyl functionalities also led to improvement of their frictional properties. The friction coefficient of the modified film is 0.05 under vacuum condition, whereas that of the pristine film shows very high value (>1).     

表面波等离子体沉积类金刚石膜结构的Raman光谱和XPS分析

本文使用Raman光谱和X 射线光电子能谱 (XPS)的分析方法对表面波等离子体沉积的类金刚石(DLC)薄膜的结构进行了研究。采用 4峰的高斯解谱的方法对不同沉积时间的膜的Raman谱进行处理 ,并由此对膜中sp3键的百分含量PD 进行了定量计算 ;同时还采用 3峰的高斯解谱方法对不同沉积时间的膜的光电子能谱进行处理 ,也对膜中sp3键的百分含量进行了计算。两种方法均得到膜中sp3含量在 2 0 %～ 4 0 %之间 ,且随沉积时间的增加而增加。     

Low energy repetitive miniature plasma focus device as high deposition rate facility for synthesis of DLC thin films

Diamond-like carbon (DLC) films were deposited on Si (1 0 0) substrate using a low energy (219 J) repetitive (1 Hz) miniature plasma focus device. DLC thin film samples were deposited using 10, 20, 50, 100 and 200 focus shots with hydrogen as filling gas at 0.25 mbar. The deposited samples were analyzed by XRD, Raman Spectroscopy, SEM and XPS. XRD results exhibited the diffraction peaks related to SiO₂, carbon and SiC. Raman studies verified the formation amorphous carbon with D and G peaks. Corresponding variation in the line width (FWHM) of the D and G positions along with change in intensity ratio (I_D/I_G) in DLC films was investigated as a function of number of deposition shots. XPS confirmed the formation sp² (graphite like) and sp³ (diamond like) carbon. The cross-sectional SEM images establish the 220 W repetitive miniature plasma focus device as the high deposition rate facility for DLC with average deposition rate of about 250 nm/min.     

Chromium-doped diamond-like carbon films deposited by dual-pulsed laser deposition

Diamond-like carbon (DLC) and Cr-doped diamond-like carbon layers were studied. DLC and Cr-DLC were deposited on silicon and titanium substrates (Ti-6Al-4V) by dual-pulsed laser ablation using two KrF excimer lasers and two targets (graphite and chromium). The composition was analyzed using wavelength-dependent X-ray spectroscopy. The Cr content increased from 2.2 to 17.9 at%. The topology and surface properties as roughness of layers were studied using scanning electron microscopy and atomic force microscopy. With the chromium concentration increased the roughness and the number of droplets. Carbon and chromium bonds were determined by Raman spectroscopy. With an increase in chromium content the I _D/I _G ratio increased. Mechanical properties of DLC films with various chromium content were evaluated. Hardness (reduced Young’s modulus) was determined by nanoindentation and reached of 51 GPa (309 GPa). Films adhesion was studied using scratch test and with concentration of chromium increased up to 20 N.     

液相电化学法制备类金刚石薄膜及其摩擦性能研究

采用自行设计的液相法沉积装置,以甲醇有机溶剂作为碳源,利用液相电化学沉积技术在不锈钢及Si基底上制备了类金刚石薄膜;用扫描电镜、Raman光谱仪表征了沉积薄膜的表面形貌和结构;用UMT-2M摩擦磨损试验机对两种沉积薄膜进行了摩擦性能测试。结果表明:经电化学沉积的类金刚石薄膜均匀、致密,表面粗糙度小;Raman光谱在1 332cm-1处有强的谱峰,与金刚石的特征峰相吻合,其中不锈钢基底上薄膜的sp3含量更高;不锈钢基底沉积膜的摩擦系数为0.12,Si片基底沉积膜的摩擦系数为0.10;不锈钢基底沉积膜的耐磨性较Si片沉积膜高。     

Pulsed laser deposition of carbon nitride films by a sub-ps laser

CN_x (0.01-2 to 0.6 mbar the nitrogen content of the films increases monotonously, as determined by X-ray photoelectron spectroscopy. Raman spectroscopy reveals that the films consist predominantly of highly amorphous carbon.     

X射线光电子能谱辅助Raman光谱分析类金刚石碳膜的结构细节

分别采用具有和不具有弯曲弧磁过滤器的两种真空阴极弧离子镀方法,在不同工艺参量下制备了类金刚石碳膜.采用Raman光谱和X射线光电子能谱(XPS),分析了不同工艺参量下的类金刚石碳膜的键结构,通过对Raman光谱的D峰、G峰和C1s电子结合能峰位、强度的对比,详细讨论了沉积工艺参量对类金刚石碳膜结构的影响.研究发现,不同工艺下具有高强度D峰Raman光谱的类金刚石碳膜,其C1s电子结合能却分别位于284.15,285.50eV,表明高度石墨化和高度金刚石化两种状态类金刚石碳膜,都可以形成具有高强度D峰Raman光谱曲线 关键词： 类金刚石碳膜 Raman光谱 X射线光电子能谱     

The influence of gas flow rate on the structural,mechanical, optical and wettability of diamond-like carbon thin films

In this research, diamond-like carbon (DLC) thin films were deposited on silicon substrates by radio-frequency plasma enhanced chemical vapor deposition method using gas mixture of CH₄ and Ar. The effect of different CH₄/Ar gas ratio on the structure, refractive index, transmission and hardness of the DLC thin films were investigated by means of Raman spectroscopy, ellipsometry, Fourier transform Infrared Spectroscopy and nano-indentation methods, respectively. Nuclear resonant reaction analysis was used to measure the amount of hydrogen and carbon in the thin films. Furthermore, wettability of the thin films was achieved by measuring of water contact angle (WCA). The results indicated that the structural properties of the diamond-like carbon thin films are strongly dependent on the composition of gas mixture. Based on ellipsometry results, refractive index of the thin films varied in the range of 1.89–2.06 at 550 nm. FTIR results determined that deposition of DLC thin films on silicon substrate led to an increase of the light transmission in IR region and these films have the potential to be used in silicon optics as the antireflective coatings in this region. Nano-indentation analysis showed that the thin films hardness changed in the range of 7.5–11 GPa. On the other hand hydrogen content and fraction of C?H bonds in the samples increased by an increase in the gas ratio of CH₄/Ar. Also, WCA measurements indicated that WCA for thin films with gas ratio of 3/7 is the most and equal to 79°.     

射频功率对类金刚石薄膜结构和性能的影响

利用直流-射频-等离子体增强化学气相沉积技术在单晶硅表面制备了类金刚石薄膜，采用原子力显微镜、Raman光谱、x射线光电子能谱、红外光谱和纳米压痕仪考察了射频功率对类金刚石薄膜表面形貌、微观结构、硬度和弹性模量的影响.结果表明，制备的薄膜具有典型的含H类金刚石结构特征，薄膜致密均匀，表面粗糙度很小.随着射频功率的升高，薄膜中成键H的含量逐渐降低，而薄膜的sp3³含量、硬度以及弹性模量先升高， 后降低，并在射频功率为100W时达到最大. 关键词： 等离子增强化学气相沉积 类金刚石薄膜 射频功率 结构和性