类金刚石碳膜的热稳定性

总结了各种ＤＬＣ膜的热稳定性及分析手段,概述了加热退火情况下ＤＬＣ膜结构,内应力的变化,评述了国内的最新研究进展,并提出了有等进一步研究的问题。     

Characterization of ion-beam-deposited diamond-like carbon films

Diamond-like carbon (DLC) films are excellent prospects for a wide range of high-technology applications but their precise structure and properties are not well understood. The purpose of the present work was to use several complementary techniques to characterize the nature, structure and microstructure of DLC films. Thin DLC films were deposited on various substrates in the presence of a Si interlayer (500 Å thick) using CH₄ ion-beam deposition at an acceleration energy of 750 eV and a current density of about 2.5 mA cm⁻². The Si interlayer was deposited by either e-beam evaporation or Si evaporation enhanced by Ar⁺ beam bombardment (1 keV). The produced DLC films were featureless, very smooth and of high hardness (2900–3300 kg mm⁻²). Auger electron spectroscopy and electron diffraction showed that the films were mainly amorphous. Their microstracture was characterized by a three-dimensional network structure with a medium-range order of about 25 nm. Fourier transform infrared and Raman spectroscopies showed that the films were mainly composed of sp³ and sp² carbon-bonded hydrogen. The sp³/sp² ratio varied from 3.2 to 4.1 and was found to depend on the nature of the Si bond layer. The results showed that the nucleation of the diamondlike structure was promoted on the Si interlayer that was deposited under Ar⁺ beam bombardment. This effect can be explained by the higher surface roughness produced in this interlayer as suggested by the reflectivity measurements. Spectroscopic ellipsometry revealed that the films had an optical band gap between 1.56–1.64 eV. The present results are consistent with previous proposals suggesting that the DLC structure is composed of small graphitelike clusters (involving fused six-fold rings) that are interconnected by sp³-bonded carbon.     

Field emission from diamond and diamond-like carbon films

Field emission from diamond and diamond-like carbon thin films deposited on silicon substrates has been studied. The diamond films were synthesized using hot filament chemical vapor deposition technique. The diamond-like carbon films were deposited using the radio frequency chemical vapor deposition method. Field emission studies were carried out using a sphere-to-plane electrode configuration. The results of field emission were analyzed using the Fowler-Nordheim model. It was found that the diamond nucleation density affected the field emission properties. The films were characterized using standard scanning electron microscopy, Raman spectroscopy, and electron spin resonance techniques. Raman spectra of both diamond and diamond-like films exhibit spectral features characteristic of these structures. Raman spectrum for diamond films exhibit a well-defined peak at 1333cm^?1. Asymmetric broad peak formed in diamond-like carbon films consists of D-band and G-band around 1550 cm^?1 showing the existence of both diamond (sp³ phase) and graphite (sp² phase) in diamond-like carbon films.     

激光辐照对类金刚石薄膜改性及损伤研究

介绍了激光损伤的检测及损伤阈值的测量方法.讨论激光辐照对类金刚石结构和性质的影响规律.并论述不同工作参数的激光对类金刚石薄膜的激光破坏行为及其损伤阈值.在此基础上分析类金刚石薄膜激光损伤的机理.还从物理特性及制备技术方面着手,比较分析金刚石及类金刚石薄膜各自的优缺点和实际应用状况,并提出类金刚石薄膜的应用前景和有待进一步研究的问题.     

Photoelectron spectroscopy characterization of diamond-like carbon films

The electronic states of diamond-like hydrogenated carbon (DLC) films were studied by synchrotron radiation photoelectron spectroscopy. The valence band spectra measured at different excitation energies show the gradual emergence of the p-pi band in relation to the sample annealing and ion bombardment amorphization. The p-pi band of the annealed DLC was characterized by localized p(z) states, while the formation of the amorphous carbon surface was accompanied by appearance of the delocalized p(z) states, which reduce the optical gap. A simple approach permitting the extraction of the 2p band shape from the photoelectron spectra is proposed.     

Electrochemical performance of diamond-like carbon thin films

Diamond-like carbon (DLC) thin films used in this study were intended for their electrochemical properties. The DLC films were deposited by a filtered cathodic vacuum arc (FCVA) process on p-type silicon (100) substrates biased at different pulse voltages (0-2000 V). The chemical bonding structures of the DLC films were characterized with micro-Raman spectroscopy and the electrochemical properties were evaluated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The DLC films showed high impedance, high polarization resistance and high breakdown potential in a 0.5 M H₂SO₄ aqueous solution, which were attributed to the high sp³ content and uniformity of the films. The excellent chemical inertness of the DLC films made them promising corrosion resistant coating materials.     

等离子体化学气相沉积类金刚石碳膜的特性及应用

类金刚石（DLC）膜是含有sp^3杂化态的亚稳态非晶碳膜，是具有极高的硬度、化学稳定性和光学透明性的半导体材料。这篇综述介绍了用等离子体化学气相沉积DLC膜的沉积方法、所制备薄膜的特性及应用，最后展望了DLC膜的发展趋势。     

类金刚石膜的性能、制备与应用(二)

类金刚石（DLC）膜是一种含有大量sp^3的亚稳态非晶碳薄膜。本文简要地介绍了DLC膜的形成原理、制备方法、发展现状,及其在机械、电子、光学、声学、生物医学等领域的应用与存在的问题。     

聚合物表面类金刚石薄膜的制备与应用

聚合物固有的柔软、易老化、不耐磨等特点,使它们的进一步应用受到限制.在聚合物表面制备1层DLC薄膜,将两种材料的优异性能结合起来,将极大地拓宽聚合物应用领域、提高聚合物应用价值.综述了近年来在聚合物表面制备类金刚石薄膜的研究进展,重点将介绍聚合物上DLC薄膜的制备方法、相关核心问题的解决及聚合物上制备DLC薄膜的应用前景.     

Optical and interfacial electronic properties of diamond-like carbon films

We have been preparing hard semitransparent carbon films on oriented polished crystal wafers of silicon, indium phosphide and gallium arsenide, as well as on KBr and quartz. Properties of the films were determined using IR and visible absorption spectroscopy, ellipsometry, conductance-capacitance spectroscopy and α particle-proton recoil spectroscopy. Preparation techniques include r.f. plasma decomposition of methane (and other hydrocarbons), ion beam sputtering and dual-ion-beam sputter deposition. Optical energy band gaps as large as 2.7 eV and extinction coefficients lower than 0.1 at long wavelengths are found. Electronic state densities at the interface with silicon as low as 10¹⁰ states eV^-1 cm^-2 were found.     

Deposition and microstructure of Ti-containing diamond-like carbon nanocomposite films

Ti-containing diamond-like carbon (DLC) films were deposited by plasma decomposition of CH₄/Ar gas mixtures with an introduction of tetrakis(dimethylamino)titanium (TDMAT, Ti[(CH₃)₂N]₄), which was used as a precursor of titanium. The films deposited were found to be nanocomposite coatings consisting of TiN nanocrystalline clusters and amorphous hydrocarbon (a-C:H), indicating that the nanocrystalline clusters were embedded in the DLC matrix. The crystallinity of TiN clusters, as well as the Ti atomic concentrations in the films, increased with an increase of substrate temperature. The substrate temperature applied to form a crystalline phase in the DLC matrix induced a graphitization of amorphous hydrocarbon matrix. The increase of volume fraction of TiN nanocrystalline clusters in the DLC matrix enhanced the mechanical properties of nanostructured coatings, although the graphite-like structural transition of DLC matrix happened due to the applied heating.     

类金刚石膜的性能、制备与应用(一)

类金刚石（DLC）膜是一种含有大量sp^3的亚稳态非晶碳薄膜。本文简要地介绍了DLC膜的形成原理、制备方法、发展现状，及其在机械、电子、光学、声学、生物医学等领域的应用与存在的问题。     

Low temperature internal friction of diamond-like carbon films

We have studied the internal friction of amorphous diamond-like carbon films prepared by pulsed-laser deposition from 0.4 to 300 K. The low temperature internal friction below 10 K is dominated by the atomic tunneling states for amorphous solids, which is a measure of structure disorder. We have tried to vary the content of sp³ carbon atoms versus sp² ones by changing laser fleunce, by doping with N and Ar, and by annealing at 500 °C for 20 min. Our results show that the internal friction varies about one order of magnitude from 2×10⁻⁵ to 2×10⁻⁴, and its value is higher with higher sp³ content when the film quality is generally considered superior. However, it is known that as-deposited diamond-like carbon films with high sp³ content are heavily stressed. Annealing and doping are used to release the stress. We conclude that in addition to tetrahedral bonding, low stress is also important in reducing structure disorder associated with the low energy tunneling states in amorphous solids.     

Some electrical properties of diamond-like carbon thin films

Diamond-like carbon (DLC) belongs to very interesting materials used for a number of practical applications. It was noted that the electrical properties of DLC films obtained by RF PCVD discharge depend substantially on the deposition conditions. The results and discussion of the electrical properties of DLC films and DLC/Si heterostructures is presented. The electrical conductivity results are explained in terms of hopping mechanism. The relation between charge transport, structure of the energy gap and the deposition conditions is discussed.     

Oxygen plasma etching of silver-incorporated diamond-like carbon films

Diamond-like carbon (DLC) film as a solid lubricant coating represents an important area of investigation related to space devices. The environment for such devices involves high vacuum and high concentration of atomic oxygen. The purpose of this paper is to study the behavior of silver-incorporated DLC thin films against oxygen plasma etching. Silver nanoparticles were produced through an electrochemical process and incorporated into DLC bulk during the deposition process using plasma enhanced chemical vapor deposition technique. The presence of silver does not affect significantly DLC quality and reduces by more than 50% the oxygen plasma etching. Our results demonstrated that silver nanoparticles protect DLC films against etching process, which may increase their lifetime in low earth orbit environment.     

Metal-doped diamond-like carbon films synthesized by filter-arc deposition

Diamond-like carbon (DLC) thin films are extensively utilized in the semiconductor, electric and cutting machine industries owing to their high hardness, high elastic modulus, low friction coefficients and high chemical stability. DLC films are prepared by ion beam-assisted deposition (BAD), sputter deposition, plasma-enhanced chemical vapor deposition (PECVD), cathodic arc evaporation (CAE), and filter arc deposition (FAD). The major drawbacks of these methods are the degraded hardness associated with the low sp³/sp² bonding ratio, the rough surface and poor adhesion caused by the presence of particles. In this study, a self-developed filter arc deposition (FAD) system was employed to prepare metal-containing DLC films with a low particle density. The relationships between the DLC film properties, such as film structure, surface morphology and mechanical behavior, with variation of substrate bias and target current, are examined. Experimental results demonstrate that FAD-DLC films have a lower ratio, suggesting that FAD-DLC films have a greater sp³ bonding than the CAE-DLC films. FAD-DLC films also exhibit a low friction coefficient of 0.14 and half of the number of surface particles as in the CAE-DLC films. Introducing a CrN interfacial layer between the substrate and the DLC films enables the magnetic field strength of the filter to be controlled to improve the adhesion and effectively eliminate the contaminating particles. Accordingly, the FAD system improves the tribological properties of the DLC films.