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1.
A systematic study of the chemical bonding in hydrogenated amorphous germanium–carbon (a-Ge1-xCx:H)alloys using X-ray photoelectron spectroscopy (XPS) is presented. The films, with carbon content ranging from 0 at. % to
100 at. %, were prepared by the rf co-sputtering technique. Raman spectroscopy was used to investigate the carbon hybridization.
Rutherford backscattering spectroscopy (RBS) and XPS were used to determine the film stoichiometry. The Ge 3d and C 1s core
levels were used for investigating the bonding properties of germanium and carbon atoms, respectively. The relative concentrations
of C–Ge, C–C, and C–H bonds were calculated using the intensities of the chemically shifted C 1s components. It was observed
that the carbon atoms enter the germanium network with different hybridization, which depends on the carbon concentration.
For concentrations lower than 20 at. %, the carbon atoms are preferentially sp3 hybridized, and approximately randomly distributed. As the carbon content increases the concentration of sp2 sites also increases and the films are more graphitic-like.
Received: 4 May 1999 / Accepted: 24 November 1999 / Published online: 24 March 2000 相似文献
2.
Synthesis of carbon nitride films by direct current plasma assisted pulsed laser deposition 总被引:1,自引:0,他引:1
Y.H. Cheng X.L. Qiao J.G. Chen Y.P. Wu C.S. Xie S.B. Muo Y.B. Sun B.K. Tay 《Applied Physics A: Materials Science & Processing》2002,74(2):225-231
Carbon nitride films were deposited by pulsed laser ablation of a graphite target under a nitrogen atmosphere at room temperature.
A direct current discharge apparatus was used to supply active nitrogen species during the deposition of carbon nitride films.
The composition and bonding structure of carbon nitride films were determined by Fourier-transform infrared (FTIR) spectroscopy
and X-ray photoelectron spectroscopy. The incorporation of nitrogen atoms in the films is greatly improved by the using of
a dc glow discharge. The ratio N/C can reach 0.34 at the discharge voltage of 400 V. Six peaks centered at 1025 cm-1, 1226 cm-1, 1381 cm-1, 1534 cm-1, 1629 cm-1, and 2200 cm-1 can be clearly distinguished from the FTIR spectra of the deposited films, which indicates the existence of C–N, C=N, and
C≡N bonds. The fraction of sp2 C, C≡N bonds, and C=N bonds in the deposited films increases with increasing discharge voltage. Deconvolution results of
C 1s and N 1s spectra also indicate that nitrogen atoms in the films are chemically bonded to sp1 C, sp2 C, and sp3 C atoms. Most of the nitrogen atoms are bonded to sp2 C atoms. Increasing the discharge voltage leads to a decrease of the fraction of nitrogen atoms bonded to sp2 C and the fraction of amorphous carbon; however, it leads to an increase of the fraction of nitrogen atoms bonded to sp3 C and the fraction of sp2 C and sp3 C atoms bonded to nitrogen atoms.
Received: 7 June 2000 / Accepted: 19 February 2001 / Published online: 27 June 2001 相似文献
3.
V. V. Uglov A. K. Kuleshov M. P. Samtsov M. V. Astashinsakaya 《Journal of Applied Spectroscopy》2006,73(3):388-393
We have used Raman scattering, elemental analysis, and structural analysis to study the effect of the concentration of incorporated
metals (Cu, Ni) on the ratio of sp2/sp3 carbon bonds in composite hydrogen-containing films a-C:H/Cu and a-C:H/Ni, formed by combining plasma-enhanced vapor phase
deposition of carbon and sputtering of the metal, using a mixture of argon and methane or acetylene gases. We have shown that
formation of a nanosized structure of metallic crystallites (2–5 nm) in the composite films leads to a significant increase
in the fraction of disordered sp3-bonded carbon clusters and a decrease in the linear dimensions of the graphite-like carbon clusters.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 344–348, May–June, 2006. 相似文献
4.
Hongliang Zhang Weidong Wu Chengshi Gong Wei Wang Zhibing He Jun Li Xin Ju Yongjian Tang Erqing Xie 《Applied Physics A: Materials Science & Processing》2010,98(4):895-900
Fe-doped hydrogenated amorphous carbon (a-C:H:Fe) films were deposited from a gas mixture of trans-2-butene/ferrocene/H2 by plasma enhanced metal organic chemical vapor deposition. X-ray photoelectron spectroscopy, Fourier transform infrared
spectra and Raman spectra were used to characterize the composition and the bonding structure of the a-C:H:Fe and a-C:H films.
Optical properties were investigated by the UV–visible spectroscopy and the photoluminescence (PL) spectra. The Fe-doped films
contain more aromatic structures and C=C bonds than the undoped films. The sp
2 carbon content and sp
2 clustering of the films increase, and aromatic-like rings’ structures become richer after Fe-doping. The Tauc optical gap
of the a-C:H:Fe films become narrower by 0.3 eV relative to the value of the a-C:H films. The PL peak shifts from 2.35 eV
of the a-C:H films to 1.95 eV of the a-C:H:Fe films, and the PL intensity of the a-C:H:Fe films is greatly enhanced. A deep
level emission peak around 2.04 eV of the a-C:H:Fe films is observed. 相似文献
5.
Diamondlike films are synthesized from gaseous hydrocarbons in a barrier discharge at atmospheric pressure. The films were
investigated using transmission electron microscopy, electron diffraction, and infrared spectroscopy. A technique for determining
the quantitative characteristics of the films (hydrogen content, ratio of different types of carbon-carbon bonds and hydrocarbon
groups) using standard samples is described. The highest-quality films were obtained from methane (ratio of hydrogen to carbon
atoms H/C=1.04, fraction of diamondlike to graphitelike bonds sp
3: sp
2=100%: 0%) and from a mixture of acetylene and hydrogen in the ratio 1:19 (H/C=0.73, sp
3: sp
2=68%: 32%).
Zh. Tekh. Fiz. 67, 100–104 (August 1997) 相似文献
6.
Experimental data are presented from studies of the structure and bond type of carbon atoms in amorphous carbon-nickel films
deposited from pulsed vacuum-arc discharge plasma sources. X-ray photoelectron spectroscopy was used. The characteristics
of the plasmon loss spectra depend significantly on the deposition parameters. Carbon exists in a mixed sp2+sp3 hybridized state in the carbon–nickel films. The ratio of sp3/sp2 carbon bonds increases when the nickel content is reduced (from 5.5 to 1.0 atomic %) and the deposition angle is increased.
The structure closest to that of diamond was with a substrate bias voltage of –80 to –100 V and a deposition angle of 90°. 相似文献
7.
M. A. Algatti R. P. Mota R. Y. Honda M. E. Kayama K. G. Kostov R. S. Fernandes T. C.A.M. Azevedo N. C. Cruz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):325-328
This paper deals with plasma polymerization processes of diethylene glycol dimethyl ether. Plasmas were produced at 150 mtorr
in the range of 10 W to 40 W of RF power. Films were grown on silicon and quartz substrates. Molecular structure of plasma
polymerized films and their optical properties were analyzed by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible
spectroscopy. The IR spectra show C–H stretching at 3000–2900 cm-1, C=O stretching at 1730–1650 cm-1, C–H bending at 1440–1380 cm-1, C–O and C–O–C stretching at 1200–1000 cm-1. The concentrations of C–H, C–O and C–O–C were investigated for different values of RF power. It can be seen that the C–H
concentration increases from 0.55 to 1.0 au (arbitrary unit) with the increase of RF power from 10 to 40 W. The concentration
of C–O and C–O–C decreases from 1.0 to 0.5 au in the same range of RF power. The refraction index increased from 1.47 to 1.61
with the increase of RF power. The optical gap calculated from absorption coefficient decreased from 5.15 to 3.35 eV with
the increase of power. Due to its optical and hydrophilic characteristics these films can be applied, for instance, as glass
lens coatings for ophthalmic applications. 相似文献
8.
Z.Y. Chen J.P. Zhao T. Yano T. Ooie 《Applied Physics A: Materials Science & Processing》2002,75(2):213-216
Raman characteristics of carbon nitride films synthesized by nitrogen-ion-beam-assisted pulsed laser deposition were investigated.
In addition to the D (disorder) band and G (graphitic) band commonly observed in carbon nitride films, two Raman bands located
at 1080–1100 and 1465–1480 cm-1 were found from our carbon nitride films. These two bands were well matched with the predicted Raman frequencies for βC3N4 and the observed Raman bands reported for carbon nitride films, indicating their relation to carbon-nitrogen stretching vibrations.
Furthermore, the relative intensity ratio of the two Raman bands to the D and G bands increased linearly with increasing nitrogen
content of the carbon nitride films.
Received: 30 October 2000 / Accepted: 5 February 2001 / Published online: 2 October 2001 相似文献
9.
I. I. Azarko V. K. Goncharov G. A. Gusakov D. R. Ismailov M. V. Puzyrev 《Journal of Applied Spectroscopy》2008,75(4):560-566
We have used Raman light scattering and electron paramagnetic resonance methods to study carbon films obtained by laser plasma
deposition, using different types of graphite targets. We have established that the films deposited in this way have a diamond-like
structure and are a nanostructured composite containing clusters of both sp2 and sp3-hybridized carbon. We have shown that an increase in structural perfection of the graphite target causes an improvement in
the structure of the carbon films obtained from it and an increase in the content of sp3-hybridized carbon in it. Thermal stimulation of the substrate during application of a coating leads to the same effect.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 539–546, July–August, 2008. 相似文献
10.
Hyun-Jung Choi Ji-Ye Kang In-Yup Jeon Soo-Mi Eo Loon-Seng Tan Jong-Beom Baek 《Journal of nanoparticle research》2012,14(2):704
Abstract
Multi-walled carbon nanotubes (MWCNTs) are functionalized at the sp2 C–H defect sites with 3,4-diaminobenzoic acid by a “direct” Friedel–Crafts acylation reaction in a mild polyphosphoric acid/phosphorous pentoxide medium. Owing to enhanced surface polarity, the resulting 3,4-diaminobenzoyl-functionalized MWCNTs (DAB-MWCNT) are highly dispersible in polar solvents, such as ethanol, N-methyl-2-pyrrolidone, and methanesulfonic acid. The absorption and emission properties of DAB-MWCNT in solution state are qualitatively shown to be sensitive to the pH in the environment. The DAB-MWCNT is used as a stable platform on which to deposit platinum nanoparticles (PNP). The PNP/DAB-MWCNT hybrid displays high electrocatalytic activity with good electrochemical stability for an oxygen reduction reaction under an alkaline condition. 相似文献11.
L.-W. Yin M.-S. Li Z.-Y. Hao Y.-J. Bai Z.-G. Gong F.-Z. Li 《Applied Physics A: Materials Science & Processing》2001,73(5):535-538
M?ssbauer spectroscopy has been used to systemically study the catalytic mechanism of Fe-based alloys in diamond formation
at high temperature–high pressure (HTHP) for the first time. M?ssbauer spectra reveal the magnetic state of the 3d electrons
of a Fe atom in the Fe-based alloy catalyst during diamond formation at HTHP. During carburization at lower temperatures than
that required for diamond formation and diamond formation in the diamond-stability region using Fe-based alloys as a catalyst,
both the quadrupole splitting QS and the isomer shift IS change from negative to positive, especially reaching a state in
which they are zero. It was indicated that the state of the 3d-shell electrons of the iron atom changes greatly during carburization
and diamond formation and that the incomplete 3d sub-bands of Fe atoms in the catalyst alloys could be filled up in proper
order by electrons of interstitial carbon atoms. During diamond formation, the unpaired 3d-shell electrons of an iron atom
in the Fe-based alloy absorb and interact with 2Pz electrons of the carbon atoms. There exist a Fe–C bonding and an electron charge transfer stage. The 2Pz electrons of the carbon atoms could be dragged into the metal atoms in the catalyst alloy and would make a transition of
triangular (sp2π) hybridization of valence electrons to tetrahedral (sp3) hybridization of valence electrons (a transition of sp2π bonds of graphite to sp3 bonds of diamond), resulting in a transition of graphite structure to diamond. Although the conclusion of this study is strictly
applicable only to Fe-based alloy catalysts, it could be considered more general because of the chemical similarities between
the transition elements used as solvent catalysts for diamond synthesis.
Received: 2 March 2001 / Accepted: 20 August 2001 / Published online: 2 October 2001 相似文献
12.
I. Pelant P. Fojtík K. Luterová J. Kočka A. Poruba J. Štěpánek 《Applied Physics A: Materials Science & Processing》2002,74(4):557-560
A novel simple method of crystallization of hydrogenated amorphous silicon (a-Si:H) thin films is described. Namely, we studied
a metal-induced crystallization enhanced by a dc electric field in sandwich p+–i–n+structures. The samples were fabricated from wide-bandgap a-Si:H with high hydrogen content (13–51 at. % H). Macroscopic islands
of a-Si:H (up to ∼1 mm in diameter) in the region between upper (CrNi) and lower (ITO) contacts crystallize instantaneously
when a sufficiently high dc electric field (≳105 V cm-1) is applied. The crystallization sets in at room temperature and ambient atmosphere and is spatially selective. A proposed
microscopic mechanism of such an easy macroscopic crystallization consists in easy diffusion of Ni and/or Ni silicides (representing
nucleation sites) through a dense network of voids in hydrogen-rich a-Si:H.
Received: 30 November 2000 / Accepted: 3 May 2001 / Published online: 27 June 2001 相似文献
13.
Enrique Camps L. Escobar-Alarcón V. H. Castrejón-Sánchez P. Tolentino-Eslava 《Applied Physics A: Materials Science & Processing》2008,93(3):759-763
Amorphous carbon thin films were deposited by laser ablation of a graphite target, using the fundamental line of a 5 ns Nd:YAG
laser. Deposition was carried out as a function of the plasma parameters (mean kinetic ion energy and plasma density), determined
by means of a planar probe. In the selected working regimes the optical emission from the plasma is mainly due to atomic species,
namely C+ (426.5 nm); however, there is also emission from other atomic species and molecular carbon. The hardness and resistivity
could be varied in the range between 10 and 25 GPa, and 108 and 1011 Ω cm, respectively. The maximum values were obtained at a 200 eV ion energy and 6×1013 cm−3 plasma density, where the maximum quantity of C–C sp3 bonds was formed, as confirmed by Raman spectroscopy. 相似文献
14.
《Current Applied Physics》2009,9(5):937-942
In this work, plasma enhanced chemical vapour deposition was used to prepare hydrogenated amorphous carbon films (a-C:H) on different substrates over a wide range of thickness. In order to observe clear substrate effect the films were produced under identical growth conditions. Raman and near edge X-ray absorption fine structure (NEXAFS) spectroscopies were employed to probe the chemical bonding of the films. For the films deposited on silicon substrates, the Raman ID/IG ratio and G-peak positions were constant for most thickness. For metallic and polymeric substrates, these parameters increased with film thickness, suggesting a change from a sp3-bonded hydrogenated structure to a more sp2 network, NEXAFS results also indicate a higher sp2 content of a-C:H films grown on metals than silicon. The metals, which are poor carbide precursors, gave carbon films with low adhesion, easily delaminated from the substrate. The delamination can be decreased/eliminated by deposition of a thin (∼10 nm) silicon layer on stainless steel substrates prior to a-C:H coatings. Additionally we noted the electrical resistivity decreased with thickness and higher dielectric breakdown strength for a-C:H on silicon substrate. 相似文献
15.
H. Minami D. Manage Y.Y. Tsui R. Fedosejevs M. Malac R. Egerton 《Applied Physics A: Materials Science & Processing》2001,73(5):531-534
We have compared the quality of carbon films deposited with magnetically guided pulsed laser deposition (MGPLD) and conventional
pulsed laser deposition (PLD). In MGPLD, a curved magnetic field is used to guide the plasma but not the neutral species to
the substrate to deposit the films while, in conventional PLD, the film is deposited with a mixture of ions, neutral species
and clusters. A KrF laser pulse (248 nm) was focused to intensities of 10 GW/cm2 on a carbon source target and a magnetic field strength of 0.3 T was used to steer the plasma around a curved arc to the
deposition substrate. Electron energy loss spectroscopy was used in order to measure the fraction of sp3 bonding in the films produced. It is shown that the sp3 fraction, and hence the diamond-like character of the films, increased when deposited only with the pure ion component by
MGPLD compared with films produced by the conventional PLD technique. The dependence of film quality on the laser intensity
is also discussed.
Received: 7 December 2000 / Accepted: 20 August 2001 / Published online: 2 October 2001 相似文献
16.
F. L. Freire Jr. C. A. Achete D. F. Franceschini G. Mariotto 《Applied Physics A: Materials Science & Processing》1994,59(6):667-672
Amorphous carbon films (a-C:H) and nitrogen incorporated carbon films [a-C:H(N)] deposited by a self-bias glow discharge have been implanted with 70 keV nitrogen ions at fluences of 0.6, 1 and 2×1017 N/cm2. The in-depth modifications caused by ion implantation were determined by means of nuclear techniques, such as Rutherford Backscattering Spectrometry (RBS), Nuclear Reaction Analysis (NRA) and Elastic Recoil Detection Analysis (ERDA), as well as by Auger Electron Spectroscopy (AES) and Raman scattering. ERDA profiles show that nitrogen implantation causes hydrogen depletion, the amount of which depends on the film composition and on the ion fluence. In a-C:H(N) films nitrogen loss was also measured. The induced structural modifications in both a-C:H and a-C:H(N) films were followed by both AES, using factor analysis, and microprobe Raman spectroscopy. They turn out to be related to the energy deposited by the incident ions. Our results indicate that the ion-beam bombardment causes in both a-C:H and a-C:H(N) films an increase of either the degree of disorder or the ratio between sp2/sp3 bonds across the hydrogen-depleted layer, which depends on the ion fluence. 相似文献
17.
AbstractUltrathin hydrogenated amorphous carbon (a-C:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) and hydrogen-free amorphous carbon (a-C) films of similar thickness deposited by filtered cathodic vacuum arc (FCVA) were subjected to rapid thermal annealing (RTA). Cross-sectional transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) were used to study the structural stability of the films. While RTA increased the thickness of the intermixing layer and decreased the sp3 content of the a-C:H films, it did not affect the thickness or the sp3 content of the a-C films. The superior structural stability of the FCVA a-C films compared with PECVD a-C:H films, demonstrated by the TEM and EELS results of this study, illustrates the high potential of these films as protective overcoats in applications where rapid heating is critical to the device functionality and performance, such as heat-assisted magnetic recording. 相似文献
18.
A. von Keudell M. Meier T. Schwarz-Selinger 《Applied Physics A: Materials Science & Processing》2001,72(5):551-556
Methyl radicals (CH3) and atomic hydrogen (H) are dominant radicals in low-temperature plasmas from methane. The surface reactions of these radicals
are believed to be key steps leading to deposition of amorphous hydrogenated carbon (a-C:H) films or polycrystalline diamond
in these discharges. The underlying growth mechanism is studied, by exposing an a-C:H film to quantified radical beams of
H and CH3. The deposition or etching rate is monitored via ellipsometry and the variation of the stoichiometry is monitored via isotope
labeling and infrared spectroscopy. It was shown recently that, at 320 K, methyl radicals have a sticking coefficient of 10-4 on a-C:H films, which rises to 10-2 if an additional flux of atomic hydrogen is present. This represents a synergistic growth mechanism between H and CH3. From the interpretation of the infrared data, a reaction scheme for this type of film growth is developed: atomic hydrogen
creates dangling bonds by abstraction of bonded hydrogen within a surface layer corresponding to the range of H in a-C:H films.
These dangling bonds serve at the physical surface as adsorption sites for incoming methyl radicals and beneath the surface
as radicalic centers for polymerization reactions leading to carbon–carbon bonds and to the formation of a dense a-C:H film.
Received: 18 July 2000 / Accepted: 12 December 2000 / Published online: 3 April 2001 相似文献
19.
A. Gutiérrez J. Díaz M. F. López 《Applied Physics A: Materials Science & Processing》1995,61(2):111-114
Amorphous carbon (a-C) films obtained by pulsed-laser ablation of graphite have been investigated by X-ray Absorption Spectroscopy (XAS). The onset of 1s
* transitions in the films lies in the gap between the
* and
* bands in graphite and very close to the absorption edge of diamond, indicating a high content ofsp
3 hybridization. A sharp feature at this onset is observed and assigned to a core exciton insp
3-hybridized disordered C atoms. Its shift of 0.5 eV with respect to the core exciton in diamond is probably due to a higher localization of the excited electron induced by disorder. A small peak coming from C–H bonds at the surface is observed and its intensity inereases with the amount ofsp
3-hybridized atoms in the sample. This can be easily explained by associating a higher amount of dangling bonds at the surface to a highersp
3 content. Polarization-dependent XAS measurements show that the angular distribution of these C–H bonds has a mean value close to the normal to the surface. 相似文献
20.
D. Guo K. Cai L.-T. Li Y. Huang Z.-L. Gui 《Applied Physics A: Materials Science & Processing》2002,74(1):69-72
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 相似文献