ICMCTF2004 Session D2-2: Diamond-like Carbon, Diamond and SiC Materials

Wednesday, April 21, 2004 8:30 AM in Room Royal Palm 4-6

Wednesday Morning

Start	Invited?	Item
8:30 AM	Invited	D2-2-1 Electron Energy Loss Spectroscopy of Carbonaceous Materials S.R.P. Silva, V. Stolojan (University of Surrey, United Kingdom) In the use of carbon thin films as a technological material, accurate information on the microstructural and chemical composition is crucial. Despite great advances in the analytical capabilities of advanced instruments, few techniques give more information than electron energy loss spectroscopy (EELS). When EELS is coupled with a transmission electron microscope, sub-nanometre resolved chemical and structural information can be obtained about the properties of the thin film. In this paper we discuss the information that is firstly available on the bond hybridisation, and ways in which to improve the accuracy of the experimentally determined pi to sigma ratio in carbon films. We then discuss electronic structure data that can be obtained by a careful analysis of the low loss region of the spectrum, together with electron density information. Joint density of state data will be compared to other material properties from amorphous carbon thin films. We use the line focussing properties associated with the quadrupoles of a Gatan Imaging Filter in a Transmission Electron Microscope to characterise the electronic and materials properties across a nano-heterojunction. This technique, when fully developed, would allow for a larger research community to have access to a relatively cheap non-contact methodology for the characterisation of the electronic properties of nano-heterojunctions. We demonstrate the technique by investigating the electronic nature of the interface in WS₂-coated multi-walled carbon nanotubes, between the coating and the nanotube. This is done by examining the effects on the plasmon resonance of the surface-plasmon coupling in anisotropic hollow nanostructures. We also examine the properties of diamond like carbon thin films on a nanometre scale in order to explore the possibility of fabricating amorphous carbon based superlattices for electronic applications.
9:10 AM		D2-2-3 Gas Barrier Property of Carbon Films Prepared under Atmospheric Pressure H. Kodama, T. Suzuki (Keio University, Japan); A. Shirakura (Kirin Brewery, Japan) Diamond-like carbon (DLC) films are well known as hard, smooth amorphous and has been applied to machining tools, hard disks, bearings and so on. Recently, researches on gas barrier and antithrombogenicity have been paid attention and partially commercialized so far. In case mass production of pet bottle coating, the use of vacuum technique will be some obstacle concerning cost. It would be great progress if DLC films could be synthesized under atmospheric pressure. We synthesized carbon films using atmospheric pressure glow (APG) equipments which we originally designed and evaluated gas barrier property of films. The purpose of our series of study is to synthesize inorganic carbon films by the AGP method. In general, the carbon films have been polymer-like materials with low density which do not have gas barrier properties at all. In this study, we synthesize and analyze carbon films under AGP circumstance and point out fundamental problems for obtaining inorganic films.
9:30 AM		D2-2-4 Formation of Initial Layer in A Self-assembled Alternating Layered Nanostructure W.Y. Wu (National Cheng Kung University, Taiwan, R.O.C.) Abstract: A conventional sputter deposition technique can produce alternating layers only when multiple sputtering targets are employed. However, we have successfully demonstrated that the use of only one single sputtering gun in a conventional sputter deposition process could lead to the formation of alternating nano-scaled layers through self-assembling. The alternating layers consist of DLC-rich and metal-rich films. It was found that the appearance of alternating layers and the periodicity depend on the type of metal and the deposition conditions. It was found thought that the initial layer determined the subsequent self-assembling of the layered nanostructures. In this study, we have therefore investigated the formation of the initial layer. A number of metal containing DLC (Me-DLC) thin films were prepared using a reactive sputter deposition technique. The target materials used in the sputter deposition include Pt, Cu, and Ni, while the reactive gas was Ar/CH₄. The Ar/CH₄ ratio was 3/1 and the power was 100W. The substrate was p type Si (100) and not heated. The working pressure was 1x10-2 torr. The resulting Me-DLC thin films have a thickness less than 20 nm. The cross sections, especially for the initial layers, of Me-DLC thin films were examined using high resolution transmission electron microscopy (HRTEM). The microstructure was investigated using micro-Raman as well as HRTEM. Optical transmittance from visible light to UV and optical band gap were also determined. Surface roughness was measured using atomic force microscopy (AFM).
9:50 AM		D2-2-5 Characteristics of DLC Coated Alumina Ceramic Seals in Medium Temperature K.Y. Lee, I.S. Jung, S.J. Kim, C.H. Ok (Pukyong National University, South Korea); C. Rincon, R. Wei (Southwest Research Institute) Ceramic seals are widely used in many severe applications such as in corrosive, high temperature and highly loaded situations especially in hot chemical water based extreme environments for automobile water pumps. Presently, polymeric materials are used as the counter part for alumina ceramic seals to reduce the ceramic-to-ceramic wear. As a result, leaks are very commonly observed from water pump during services. Consequently, it is needed to improve the surface properties of the ceramic seals using a surface modification technique such as a thin film coating process to meet the increasing demand of more stable, more durable and lower friction of coefficient in those extreme environments. To meet these challenges, we have applied DLC (diamond-like carbon) coatings on alumina seals using a PIID (plasma immersion ion deposition) technique. The DLC coated specimens have been tested under a wider range of temperature conditions, from room 25°C up to 350°C in dry air to see the survivability of the DLC coatings. Then, wear tests were carried out using a high temperature pin-on-disk tribo-tester. After that, the wear-tested specimens were analyzed using SEM with EDS to characterize the worn surfaces as well as the cross sections of the DLC films. Morphological changes of the DLC coated surfaces before and after the wear tests were studied using AFM. In addition, AES, XPS and GXRD were adopted to characterize the elemental changes of the DLC coatings during the wear tests at such high temperatures. Finally, the wear characteristics of the DLC coatings on commercial alumina disc seals in the medium temperature range are presented in detail.
10:10 AM		D2-2-6 Synthesis of Nano-Crystalline Carbide Diamond-like-Carbon (DLC) using Dual Plasma Implantation and Deposition R.K.Y. Fu, Y.F. Mei, Y. Fu, G.G. Siu, P.K. Chu (City University of Hong Kong) Metal doping of amorphous carbon can result in the formation of metal carbides which exhibit good adhesion, high hardness, low friction loss, stable thermal ability and good conductivity. A dual plasma technique comprising metal arc plasma and carbon gas plasma is used in this work to fabricate metal-containing diamond-like-carbon (Me-DLC). Chemically, the ionized carbon is more reactive in forming bonds with the adjacent metal atoms so as to build up an amorphous network with crystalline carbide in a low temperature deposition processes. Several deposition parameters such as substrate bias, carbon gas flow rate and metal plasma output are experimented to prepare the optimal Me-DLC films. The surface morphology, chemical composition and microstructure are studied using atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. In additions, the thermal ability of the films is evaluated by annealing at a series of temperatures. Other characteristics of the films such as mechanical properties, optical properties and conductivity are also assessed and presented in this paper.
10:30 AM	Invited	D2-2-7 Deposition and Characterization of Silicon Carbide Epitaxial Layers M. Skowronski (Carnegie Mellon University) Silicon carbide-based electronic devices are uniquely suited for high voltage high power applications. This class of devices is possibly the most demanding in terms of the quality of the material, including ability to deposit thick films with perfect surface morphology, very low and uniform dopant concentrations, long minority carrier diffusion length, and very low extended defect densities. This presentation will focus on two versions of Chemical Vapor Deposition technique, namely silane- and silicon tetrachloride-based processes and summarize current issues in layer quality with emphasis on extended defect morphology and nucleation mechanisms. The topics is specific interest include: propagation of dislocations from the SiC substrate and the effect of image force on their propagation in the epilayers, nucleation of dislocation pair arrays, strain due to doping differences and strain relaxation in heavily-doped films, nucleation and morphology of basal plane stacking faults, and origin of surface morphology defects such as carrots and arrows.
11:10 AM		D2-2-9 A New High Rate Deposition Method of SiC Wear Coatings at Room Temperature and Atmospheric Pressure A.R. Torosyan (National Academy of Sciences of the Republic of Armenia); R. Ziervogel, M. Becker, T. Schuelke (Fraunhofer USA) A novel technique called mechano-chemical deposition (MCD) has been developed to deposit ceramic and carbon based coatings on components for wear protection. MCD operates at atmospheric pressure and room temperature conditions and allows for high deposition rates. The equipment orders of magnitude less expensive than vacuum systems for chemical and physical vapor deposition as well as thermal spray equipment. MCD systems can be easily scaled to different part sizes and geometries. Three dimensional parts as well as inside diameter surfaces can be coated. The deposition technique combines the characteristics of mechanical alloying and shot peening and can be applied either separately or in combination with the traditional coating technologies. To demonstrate the capabilities of the technique we deposited silicon carbide (SiC) coatings on flat as well as three-dimensional titanium and aluminum parts. SiC is an excellent abrasion resistant coating. The morphology and Tribological properties have been determined by conventional analysis methods.
11:30 AM		D2-2-10 Silicon Carbon Nitride Films Produced by RF Magnetron Sputtering using Ammonia or Nitrogen as Reactive Gas. R.A. Simao, R.T. Britto, C.A. Achete (Universidade Federal do Rio de Janeiro, Brazil); M.D. Michel, C.M. Lepienski (Universidade Federal do Parana, Brazil) Silicon carbon nitride films have been successfully synthesized by reactive magnetron sputtering using a target of SiC and N₂⁺ Ar as reactive gases. However, it remains open the discussion about the role of each gas on the deposition process and films properties. In this work we present the results obtained using either nitrogen or ammonia as reactive gas to produce SiCN by r. f. magnetron sputtering. The films were prepared using a sintered SiC target and nitrogen / argon or ammonia / argon mixture gas. Different gas range flows were used to describe the properties. Fourier Transform Infrared Spectrometer (FTIR) was used to characterization of the films. The results revealed different chemical bonds in the film, such as CâN, C=N, CâN, SiâN and SiâC, when different gases were used. We also observed a influence of deposition condition over deposition rates, hardness and internal stress. Atomic Force Microscopy (AFM) was used to describe differences in surface morphology of the deposited films in order to understand the variation in the measured of internal stress. Auger Spectroscopy (AES) was used to sputter depth profiles.
11:50 AM		D2-2-11 New Method for Surface Modification and Hard Coatings A.R. Torosyan (National Academy of Sciences of the Republic of Armenia); M. Becker, T. Schuelke (Fraunhofer USA) A new approach to modify metal surfaces and deposit hard coatings is introduced. It is well known that the improvement of surface quality and its activation are integral parts of many deposition techniques. It has also been established that the mechanical impact processing of solids with milling balls significantly activates solid surfaces by increasing the speed of chemical interactions. Moreover, the residual compression acts to inhibit crack growth, improves wear properties, and prolongs fatigue life of components treated in this way. The high degree of hardening and low roughness of the substrate surface achieved at this stage leads to a better quality of the resulting coatings. The method discussed in this paper is based on the in-situ mechano-chemical processing of the substrate and the formation of hard coatings. All these processes take place at room temperature, making them attractive to coat low-alloy aluminum and steel components. As an interesting example of surface modification, namely its purification and hardening, the mechano-chemical processing of low-carbon containing steel substrates in organic solvents and its doping with carbon was chosen. Simultaneously, the deposition, characterization, and application of diamond containing Al_xO_x micro-composite films are presented. The latter system was selected due to its superior adhesion and mechanical properties. Some mechanical properties of the modified layers and formed coatings were identified by means of strain-strength and micro-hardness tests. It has been shown that mechanical processing in reducing mediums by removing unwanted impurities brings significant improvements of the substrate micro-hardness. Laser-induced surface acoustic waves (SAW) have been used to determine the Young's modulus of the film material.