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1.
From the viewpoint of hardness, chemical bonding states of nitrogen-doped hydrogenated amorphous carbon film were characterized by Ultra violet (UV) Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. UV Raman spectra revealed that disorder of the structure in nitrogen-doped hydrogenated amorphous carbon was promoted by applying higher bias voltages in the preparation. FT-IR spectra showed that NH bonds decreased and sp3Csp3N bonds increased with the increase of the bias voltages. The content of sp3Csp3N bonds was maximized at the bias voltage of −800 V. We found out a guarantee that the content of sp3Csp3N bonds against bias voltages correlated with the hardness obtained by nanoindentation test. The structural disorder and the increase of sp3Csp3N bonds are possible source of the hardness in the case of nitrogen-doped hydrogenated amorphous carbon. 相似文献
2.
Navneet SoinSusanta Sinha Roy Sekhar Chandra RayPatrick Lemoine Md. Anisur RahmanPaul D. Maguire Sushanta K. MitraJames A. McLaughlin 《Thin solid films》2012,520(7):2909-2915
Microstructural properties of ultrathin (1-10 nm) tetrahedral amorphous carbon (ta-C) films are investigated by Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, X-ray Photoelectron Spectroscopy, Raman spectroscopy and Atomic Force Microscopy (AFM). The CK-edge NEXAFS spectra of 1 nm ta-C films provided evidence of surface defects (C―H bonds) which rapidly diminish with increasing film thickness. A critical thickness for stabilization of largely sp3 matrix structure distorted by sp2 sites is observed via the change of π*C═C peak behavior. Meanwhile, an increase in the film thickness promotes an enhancement in sp3 content, the film roughness remains nearly constant as probed by spectroscopic techniques and AFM, respectively. The effect of thickness on local bonding states of ultrathin ta-C films proves to be the limiting factor for their potential use in magnetic and optical storage devices. 相似文献
3.
Raman scattering analysis revealed that the structure of carbon (C) films prepared by pulsed laser deposition at room temperature is predominantly amorphous and the structure of amorphous C nitride (a-CNx) films can be changed with varying substrate temperatures (ST) from 20 to 500 °C. The deposited a-CNx films are composed of C-N, C-N and C-O bonded materials and the C-N and C=N bonds are increased with ST. We have found no other obvious peaks can be distinguished in the range 900 to 2300 cm−1 in which several peaks always appear in a-CNx films. The spectra were deconvoluted into Raman D and G peaks and the structural parameters are determined. The upward shifts of Raman G peak towards 1592 cm−1 shows the evidence of a progressive formation of crystallites in a-CNx films upon increase of ST. While, the upward shifts of Raman D peak towards 1397 cm−1 have been related to the decreased of bond-angle disorder and sp3 tetrahedral bonding in its structure. Raman FWHM and IDIG also indicate that N incorporation with increased of ST caused an increase in the number and/or size of graphitic domains in the a-CNx films. 相似文献
4.
DongHyeok LeeJinNyoung Jang KwangHo KwonSukJae You BonJu LeeMunPyo Hong 《Thin solid films》2011,519(20):6703-6707
The effects of argon neutral beam (NB) energy on amorphous carbon (a-C) films were investigated, the a-C films were deposited by a neutral particle beam assisted sputtering (NBAS) system. The energy of the neutral particle beam can be directly controlled by a reflector bias voltage as a unique operating parameter of the system. The results from the analysis by Raman spectra, Fourier transform infrared (FT-IR), UV-visible spectroscopy and electrical conductivity indicate the properties of the amorphous carbon films can be manipulated by simply adjusting the NB energy (or reflector bias voltage) without changing any other process parameters. By increasing the reflector bias voltage, the amount of cross-linked sp2 clusters as well as the sp3 bonding in the a-C film coating from the NBAS system can be increased effectively and the composition of carbon thin films can be changed from a nano-crystalline graphite phase to an amorphous carbon phase. In addition, the deposition rate increases with reflector bias voltage due to additional sputtering at the carbon reflector without any variation of physical and electrical properties of the a-C film. 相似文献
5.
A selective oxidation technique for diamond films based on the extended exposure to UV light in air at room temperature was developed and studied by Raman Spectroscopy and Scanning Electron Microscopy. The diamond films were synthesized by the combustion flame technique in open atmosphere by using an oxy-acetylene gas mixture as the carbon source. A 125 W UV lamp was used to irradiate the films in the wavelength range of 180–250 nm, from 2 to 10 days. The Raman spectrum from the as-deposited diamond films shows the typical band at 1333 cm–1, characteristic of the sp
3diamond structure, with a certain nondiamond or graphite content. After UV irradiation, graphite was selectively oxidized and partially removed without oxidation of diamond, indicating that the strong reaction of ozone (O3) and atomic oxygen (O·) produced by the UV irradiation oxidized the graphite, even at room temperature, without the need of an additional heating source. The oxidation of graphite was best observed after 2 days of UV treatment. A sensible improvement in the diamond film quality was obtained after 2 days of irradiation, as revealed by the sharpening of the corresponding Raman band. 相似文献
6.
Kazuhiro Yamamoto 《Vacuum》2009,84(5):638-7152
Hydrogen-free carbon films with the various sp3 bond fractions between 83% and 40% were prepared by mass-separated ion beam deposition (MSIBD). These sp3 bond fractions were obtained by electron energy loss spectroscopy (EELS). Chemical bond analysis of these carbon films was performed by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Raman spectroscopy, and the comparison of these methods was examined. XPS C1s spectra of carbon films show two contributions at the energies of 284.5 and 285.5 eV, which are originated from sp2-bonds and sp3 bonds, respectively. The sp3 bond fractions obtained by XPS are in good agreement with the values given by EELS. The fine structure of AES spectra at the kinetic energy region between 245 and 265 eV reflects the sp3 bond fraction. AES spectra are changed from the diamond-like feature to the graphite-like one with decreasing the sp3 bond fraction. Raman spectra show two broad peaks of G band and D band, the ratio of two peak intensities is independent on the sp3 bond fraction of films. The shift of G peak position has a correlation with the sp3 bond fraction in the sp3 bond rich region. 相似文献
7.
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. 相似文献
8.
Wegelin Frederik Christian Ziethen Ralph Ohr Dipl.‐Phys. Marc Neuhäuser Dipl.‐Phys. Heinz Hilgers Dr. Gerd Schönhense Prof. Dr. 《真空研究与实践》2001,13(5):287-292
Carbon and carbon nitride films are widely used as protective overcoats. Especially in magnetic hard disk drive industry there is a need for wear resistant and corrosion preventing overcoats with a thickness of some few nanometers. X‐ray Photoemission Electron Microscopy is a versatile tool to analyze carbon overcoats among others. Information about local bonding environment can be achieved by recording X‐ray Absorption Near Edge Structures (XANES). CVD DLC, a‐C and CNx coating have been analyzed. The fractions of sp2‐hybridized carbon atoms have been determined for a‐C overcoats and its correlation to mechanical properties could be shown. A scratch test has been performed on a CNx overcoat on a magnetic disk and analyzed with X‐PEEM afterwards. 相似文献
9.
10.
In this work, we report the laser irradiation effects on the properties of various types of amorphous hydrogenated carbon (a-C:H) films. The influence of the initial carbon film (hydrogen concentration, sp3/sp2 ratio, and sp2 clustering) is studied. The results show that a loss of hydrogen and an increase of the sp2 phase are the main processes in the laser power range between 1.8 and 5 MW/cm2. Only these processes are stronger for “more polymer-like” and “graphite-like” films than for “more diamond-like” films. 相似文献
11.
The effect of annealing temperature on the structure of diamond-like carbon films by electrodeposition technique 总被引:1,自引:0,他引:1
Diamond-like films have been prepared by electrodeposition in liquid phase. The films consist of a little amount of hydrogen, which can be removed by annealing at below 600 °C. The Raman signal of annealing films suggested: (1) the intensity ratio ID/IG increases which suggested that the crystallites grew in number and size with increasing temperature; (2) the D-line position changes from 1380 to 1346 cm–1, and the G-line position from 1580 to 1604 cm–1 which indicated that partially tetrahedral bonds have been broken and have transformed to trigonal bonds, (3) the linewidths of the D and G-line decrease with the increasing annealing temperature. These results indicated that the primary bonding in the films changed gradually from sp3-bonded to sp2-bonded carbon with increasing annealing temperature, i.e., graphitization. 相似文献
12.
Instead of the sophisticated deposition processes and boron sources reported in literature, the study used the radio frequency magnetron sputtering method to prepare boron-doped diamond-like carbon (DLC) films with p-type conduction. The adopted sputtering targets were composed of boron pellets buried in a graphite disc. The undoped DLC films prepared exhibited n-type conduction, based on the Hall-effect measurement. For boron content ≥ 2.51 at.%, the films showed semiconductor behavior converted from n-type to p-type conduction after annealing at 450 °C. B-DLC films with a boron content of 5.91 at.% showed a maximum carrier concentration of 1.2 × 1019 cm−3, a mobility of 0.4 cm2/V s, and an electrical resistivity of 1.8 Ω cm. The results of XPS and Raman spectra indicated that the motion of boron atoms was thermally activated during post-annealing, helping promote the formation of C-B bonds in the films. Moreover, the doping of boron in DLC films decreased sp3 bonding and facilitated carbon atoms to form sp2 bonding and graphitization. 相似文献
13.
We have produced hydrogen-free tetrahedral amorphous carbon films with different densities and Young's modulus by coating silicon with a filtered vacuum arc under different angles. The films were modified with a pulsed laser (wavelength 355 nm) into sp2 rich amorphous carbon and nano crystalline carbon films. The graphitization threshold of the films depends on the film thickness as well as on the carbon density. Simulations of the optical absorption of the different carbon films permitted to confirm the experimental results. On the other side, the delamination threshold of carbon films increases with the film thickness and was found to be controlled by thermal properties of the film. The thin film graphitization and delamination is investigated by optical microscopy, atomic force microscopy, scanning electron microscopy and Raman spectroscopy. 相似文献
14.
Anupam Midya Venkatesh Mamidala Jia‐Xiang Yang Priscilla Kai Lian Ang Zhi‐Kuan Chen Wei Ji Kian Ping Loh 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(20):2292-2300
A polymer based on fluorene, thiophene, and benzothiadazole as the donor–spacer–acceptor triad is covalently coupled to reduced graphene oxide (rGO) sheets via diazonium coupling with phenyl bromide, followed by Suzuki coupling. These polymer–graphene hybrids show good solubility in organic solvents, such as chloroform, tetrahydrofuran (THF), toluene, dichlorobenzene, and N,N‐dimethylformamide (DMF), and exhibit an excellent optical‐limiting effect with a 532‐nm laser beam. The optical‐limiting threshold energy values (0.93 J cm?2 for G–polymer 1 and 1.12 J cm?2 for G–polymer 2) of these G–polymer hybrids are better than that of carbon nanotubes (3.6 J cm?2). 相似文献
15.
C. Demaria P. Benzi A. Arrais E. Bottizzo P. Antoniotti R. Rabezzana L. Operti 《Journal of Materials Science》2013,48(18):6357-6366
The growth of amorphous hydrogenated germanium carbide (a-GeCx:H) alloys was performed with high deposition rates by radiolysis chemical vapor deposition (X-ray) of germane/allene (GeH4/C3H4, 70/30 %) mixtures at different irradiation times. The experimental deposition parameters were correlated to the composition, the structural features, and the optical coefficients of the films, as studied by different spectroscopic techniques, namely, IR, Raman, and UV–Vis. It was observed that the increase of irradiation time yields a more hydrogenated and more disordered material, with abundant formation of sp3 CH2 groups, characterized by high band-gap values. In addition, we report the effects of thermal annealing on bonding structures and optical properties of the amorphous germanium carbon alloys. The decrease of hydrogen extent, together with the enhancement of sp2 C bonds present and amorphous-to-crystalline germanium phase transition, contribute to a larger structural order of the material and to the reduction of the optical gap at higher temperatures. 相似文献
16.
Effects of an amorphous silicon underlayer on the evolution of microstructure and hardness of an amorphous carbon film annealed at 900 °C for 0.5-1.5 h were investigated. The two-layer carbon/silicon film after annealing resulted in higher sp2/sp3 bonding ratio but lower hardness reduction compared to the single carbon film at the same total film thickness. The improved hardness reduction of the high-temperature annealed carbon film is attributed to the formation of polycrystals of the amorphous silicon together with the residual compressive stress of the two-layer C/Si films. 相似文献
17.
Zicheng Zuo Dan Wang Jin Zhang Fushen Lu Yuliang Li 《Advanced materials (Deerfield Beach, Fla.)》2019,31(13)
The development of carbon materials offers the hope for obtaining inexpensive and high‐performance alternatives to substitute noble‐metal catalysts for their sustainable application. Graphdiyne, the rising‐star carbon allotrope, is a big family with many members, and first realized the coexistence of sp‐ and sp2‐hybridized carbon atoms in a 2D planar structure. Different from the prevailing carbon materials, its nonuniform distribution in the electronic structure and wide tunability in bandgap show many possibilities and special inspirations to construct new‐concept metal‐free catalysts, and provide many opportunities for achieving a catalytic activity comparable with that of noble‐metal catalysts. Herein, the recent progress in synthetic methodologies, theoretical predictions, and experimental investigations of graphdiyne for metal‐free catalysts is systematically summarized. Some new perspectives of the opportunities and challenges in developing high‐performance graphdiyne‐based metal‐free catalysts are demonstrated. 相似文献
18.
Plasma-deposited amorphous hydrogenated carbon (a-C:H) films are determined both by the carbon sp3/sp2 bonding ratio and the hydrogen content. As the energy of the bonds C-H (C-C) is considerably smaller than that of CC or CC bonds, so the hydrogen concentration and the physical properties of a-C:H films can be varied by laser irradiation. The properties of produced films were investigated by Rutherford backscattering (RBS) and elastic recoil detection (ERD) spectroscopy, null-ellipsometry, and Raman spectroscopy (RS). It was found that films with higher hydrogen concentration are more sensitive to nanosecond pulse laser irradiation. 相似文献
19.
Evaluation of microstructures and mechanical properties of diamond like carbon films deposited by filtered cathodic arc plasma 总被引:1,自引:0,他引:1
Diamond-like carbon (DLC) films were deposited by a cathodic arc plasma evaporation (CAPD) process, using a mechanical shield filter combined with a magnetic filter with enhanced arc structure at substrate-bias voltage ranging from − 50 to − 300 V. The film characteristics were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). The mechanical properties were investigated by using a nanoindentation tester, scratch test and ball on disc wear test. The Raman spectra of the films showed that the wavenumber ranging from 900 to 1800 cm− 1 could be deconvoluted into 1140 cm− 1, D band and G band. The bias caused a significant effect on the sp3 content which was increased with the decreasing of ID/IG ratio. The XPS spectra data of the films which were etched by H+ plasma indicated the sp3 content are higher than those of the as-deposited DLC films. This implied that there is a sp2-rich layer present on the surface of the as-deposited DLC films. The nanoindentation hardness increased as the maximum load increased. A 380 nm thick and well adhered DLC film was successfully deposited on WC-Co substrate above a Ti interlayer. The adhesion critical load of the DLC films was about 33 N. The results of the wear tests demonstrated that the friction coefficient of the DLC films was between 0.12 and 0.2. 相似文献
20.
Shin-ichi Aoqui Tamiko Ohshima Tomoaki Ikegami Kenji Ebihara 《Science and Technology of Advanced Materials》2013,14(3-4):533-537
Pulsed laser deposition (PLD) technique has been widely used in thin film preparation because of its wonderful and excellent properties and amorphous carbon nitride (CNx) thin films are recognized to have potential for applications like hard coating and electron field emission device. We have deposited CNx thin films by KrF excimer laser – (λ= 248 nm) ablation of pure graphite target in pure NO gas ambient condition. In this paper, we have prepared the CNx thin films at various ambient NO gas pressure of 1.3–26 Pa and laser fluence of 2– 5J cm?2 on Si (100) substrate. We consider that the hardness of CNx thin films improves due to the increase the nitrogen/carbon (N/C) ratio. The N/C ratio depended on the ambient NO gas pressure and laser fluence. We obtainedthe maximum N/C ratio of 1.0 at NO 3.3 Pa. The typical absorption of CN bonds such as sp2 C–N, sp3 C–N, G band and D band were detected from the infrared absorption measurement by FTIR in the deposited CNx thin films. 相似文献