Optimized AR Diamond-Like Coatings On Infrared Windows

Hydrogenated amorphous diamond-like carbon (DLC) films produced by RF-glow discharge deposition from hydrocarbon mixtures in a parallel diode-type plasma reactor were investigated. The DLC films were obtained at various gas mixture compositions and bias voltages (Vb). Raman spectra of DLC films in the range 1000 - 1800 cm -1 were analyzed. Our results are given in terms of I(D)/I(G) intensity ratio, bands position, and width (FWHM) as a function of bias voltage and gas mixture. The analysis of Raman spectra shows that bias voltage value is critical for the DLC films structure. The increase of Vb from -200 V to -700 V results in the essential high-frequency shift of G- and D-bands and change of their intensities ratio I(D)/I(G) from 0.64 (Vb equals 200 V) to 3.2 (Vb equals 700 V). Similar high-frequency shift, change of FWHM and I(D)/I(G) intensities ratio were observed at the variation of methane concentration in gas mixture composition from 100 to 20%.

Diamond-like carbon (DLC) films as a hard protective coating have achieved great success in a diversity of technological applications. However, adhesion of DLC films to substrates can restrict their applications. The influence of a silicon interlayer in order to improve DLC adhesion on glass substrates was investigated. Amorphous silicon interlayer and DLC films were deposited using plasma enhanced chemical vapor deposition from silane and methane, respectively. The bonding structure, transmittance, refraction index, and adherence of the films were also evaluated regarding the thickness of the silicon interlayer. Raman scattering spectroscopy did not show any substantial difference in DLC structure due to the interlayer thickness of the silicon. Optical measurements showed a sharp decrease of transmittance in the ultra-violet region caused by the fundamental absorption of the light. In addition, the absorption edge of transmittance shifted toward longer wavelength side in the ultra-violet region as the thickness of the silicon interlayer increased. The tribological results showed an increase of DLC adherence as the silicon interlayer increased, which was characterized by less cracks around the grooves.

A superhard diamond-like carbon film

The electronic properties of amorphous diamondlike carbon (DLC) films on silicon were examined for their capability for application to electronic devices. Metal-insulator-semiconductor (MIS) diodes and p-n heterojunction devices were created and characterized. The films used were grown using rf plasma assisted CVD of methane. They were grown on n-type silicon (100) wafers. Their structural composition was identified by Raman spectroscopy, ellipsometry, and x rays. They showed an insulating behavior and they were suitable for the creation of MIS devices. They showed extremely low internal conductivity due to defect currents. This conductivity showed a behavior of the form I∼T1/4. Then the density of trapping states at the silicon/carbon interface was measured using the conductance technique. The aim of investigating the nature and behavior of these states was to determine the magnitude of the density of states and try to find a way to reduce it. Thus optimization of the DLC/silicon interface could be made, for future reference to the construction of heterojunction devices containing the DLC/silicon configuration. The values of the density of states were of the order of 1011–1012 cm−2 eV−1. Annealing had the effect of reducing the magnitude of the Dit. The ion implantation technique was used to transform the insulating DLC films into semiconducting by adding boron ions as dopants to achieve p-type conductivity. Thus p-n heterojunction devices were made, having silicon as one of the elements and DLC as the other element. Four different doses of boron were implanted, producing different conducting properties of the DLC films. Those devices performed like Schottky diodes for low boron doses and like p-n diodes for high doses.

To achieve ultra-high recording density, flying heights of less than one micro-inch are required which lead to a tribology of the HDI (head-disk interface) limiting disk drive design. Various amorphous diamond-like or DLC type carbon films have been developed for wear protection. At first pure carbon(C) sputtered films were used, followed by C:H (hydrogenated carbon) and C:N (nitrided carbon) films with generally superior wear performance. Because of the near- or quasi-contact nature of the wear process, we have used mainly (CDT)CONTINUOUS DRAG TESTING for our evaluations, along with identifying bond character, nanohardness, microscopies of surfaces and bulk of films etc., to establish the nature of initial wear damage and dependence on as-deposited film structure (atomic & electronic). The purpose: Control deposition processes-to control the structure-thus control properties.

Low-emissivity coating of amorphous diamond-like carbon/Ag-alloy multilayer on glass

Photoluminescence properties of diamond-like amorphous carbon films

HREM study of ultra-thin, amorphous carbon films and structural changes of carbon forms to diamond under ion bombardment

CVC's inexpensive plasmasource accessory

The resistance of thin diamondlike carbon (DLC) films to anodic breakdown in aqueous electrolytes was investigated using voltammetry. The films were less than 0.5 μm thick and were deposited on type 301 stainless steel substrates using plasma-assisted chemical vapor deposition (PACVD) from either methane, acetylene, or 1,3-butadiene precursors with argon or hydrogen as diluent. A 10 nm thick polysilicon (PS) film was plasma-deposited prior to DLC film deposition to improve adhesion. The electrolytes used for corrosion testing were mixtures of 0.1 M NaCl and 0.1 M Na2SO4 and 0.1 M HCl and 0.1 M Na2SO4 in de-ionized water. The measured anodic current was lowest for the films deposited from butadiene and highest for those deposited from methane. The anodic current also increased with an increase in the hydrogen content in the feed gas mixture. In addition, the DLC films deposited at higher gas flow rates offered more resistance to anodic dissolution than those deposited at lower gas flow rates. Annealing improved the film performance. There appears to be an optimum DLC film thickness which provides the maximum resistance to anodic dissolution. In the best case, the DLC films reduced the anodic dissolution of bare stainless steel by about 4 orders of magnitude in the passive region. Atomic force microscopy studies of coated and uncoated stainless steel showed that the DLC films conformed to the steel substrate surface and had no effect on surface roughness, while DLC coated silicon substrates showed no evidence of pores.

Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetic and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of 3- and 4-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetic of PLD growth results in films becoming more ``diamondlike'', i.e. increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to material within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film.

Field emission properties of non-hydrogenated DLC films prepared by a novel laser evaporation technique has been studied. A key feature of the novel technique is using a scanning pulsed laser beam, irradiating a graphite target with a focused beam and constant laser power density. The technique has a main advantage of easy scale up for uniform and large area coating. The results show that the DLCfilms exhibit an electron emission thresholdfield as low as 10-20 V/pm and a current density of 100 mA/cm2 at 40 V/pm. In addition, a bright image of cathodoluminescence has been successfully obtained ?om afield emission display with the DLCfilm emitter. I. INTRODUCTION It has been reported that carbon-based material field emitters [l-71 have a high potential for the applications of a field emission display (FED). The carbon-based materials exhibit a low effective work function, extraordinary hardness, chemical inertness and high thermal conductivity which are apparently suitable for high performance electron emitters. Among these materials, non-hydrogenated diamondlike carbon (DLC) films are believed to be a primary candidate material for an FED due to its low temperature deposition process together with relatively high thermal stability which is compatible with a current state of the art of a vacuum packaging process using frit sealing [S, 91. In this contribution we present a novel laser evaporation technique for large area deposition of non-hydrogenated DLC films. Preliminary results for the field emission analysis of these films show an electron emission threshold value as low as 10-20 V/pm and thermal stability enough to endure the frit sealing process. 11. EXPERIMENTAL The novel technique uses a scanning pulsed laser beam with nominal power densities as high as 10'0-10'3 watts/cm2. The laser beam, with the beam spot size kept constant, sweeps a graphite target surface to produce a moving laser plasma, which is then solidified onto a moving substrate thereby forming a non-hydrogenated DLC film. The main advantage of this technique is that it can provide a uniform and large area DLC coating which has been very difficult to be met by a conventional pulsed laser deposition method [lo-121. Up to now a 11 inch DLC film was successfully deposited by this technique. The schematic illustration of the novel system was shown in Fig. 1. The DLC films were prepared on MO or Cr metal coated glass substrates to measure field emission characteristics. A finely polished glass plate embedded with stainless steel rods or a glass plate with patterned IT0 film was used as an anode. The anode plate was separated from the cathode by using a 20 pm thick metal film as a spacer. A phosphor coated IT0 glass substrate was used as an anode to observe a cathodoluminescent pattern. I-V characteristics of the samples were measured in UHV environment better than low lo-*

Diamond-like carbon (DLC) films have attracted much attention because of their excellent performance; however, the low anti-laser damage ability of such films seriously restricts their applicability to high-power infrared optical windows or laser system, etc. To overcome this problem, in this study, Titanium (Ti) electrodes were deposited on DLC films directly, forming a transverse bias field on films' surfaces. The damage morphology under laser irradiation was observed both before and after the bias field was applied, and Raman spectroscopy was used to analyse chemical structure of DLC films. It was shown that as the I(D)/I(G) ratio increased, the sp3 content decreased in laser-irradiated regions of DLC films when a bias electric field was not applied. When the bias electric field was applied to DLC films, it could effectively stop the content changing from sp3-bonding carbon to sp2-bonding carbon, prevent the formation of sp2 clusters, and slow down the films graphitisation process. The fast thermal diffusion improves the DLC films' anti-laser damage ability ultimately.

Diamond-like carbon (DLC) films is a metastable form of amorphous carbon containing a significant fraction of Sp3 bond. DLC films have been characterized by a range of attractive mechanical, chemical, tribological, as well as optical and electrical properties. In this study DLC films were prepared by the RF magnetron sputter system on substrates using graphite target. The effects of the post annealing temperature on the Property variation of the DLC films were examined. The DLC films were annealed at temperatures ranging from 300 to using rapid thermal process equipment in vacuum. The variation of electrical property and surface morphology as a function of annealing treatment was investigated by using a Hall Effect measurement and atomic force microscopy. Raman and X-ray photoelectron spectroscopy analyses revealed a structural change in the DLC films.

Diamond-like carbon (DLC) films have attracted great interest due to their outstanding mechanical, biocompatibility, thermal, optical and electrical properties. The DLC films can be produced by microwave plasma chemical vapor deposition (MPCVD) using Argon, methane and hydrogen mixed gases. The film properties depend strongly on the experimental parameters such as substrate temperatures; microwave power, process pressure and hydrogen concentration (H2/Ar+CH4+H2). In this study, the properties of nanomechanics of DLC films with various experimental parameters are firstly discussed which include hardness and Young’s modulus characterizing by depth-sensing nanoindentation technique. The nanoindentation is an excellent method for measuring nanomechanical properties of both bulk and thin films. The probe was conducted using a Berkovich diamond tip. To find the optimized process parameters, the statistical and mathematical response surface methodology (RSM) is used to model and analyze the effect of substrate temperature (T), microwave power (W), process pressure (P) and hydrogen concentration (H) on the properties of nanomechanics of DLC films. The central composite experimental design (CCD) is used to evaluate the interaction parametric effects of multiple experimental variables on process response (hardness and Young’s modulus). The predictive quadratic model proposed herein considering the analysis of variance (ANOVA) are proved to fit and predict values of the hardness and Young’s modulus close to those readings recorded experimentally. The most significant influential factors for maximizing the hardness and Young’s modulus have been identified from the ANOVA table. The RSM technique is demonstrated to be a powerful tool in exploration of the manufacturing parameters space of complex physical process of DLC films deposition by MPCVD.