共查询到20条相似文献,搜索用时 359 毫秒
1.
利用微波等离子体化学气相沉积(MPCVD)技术,采用偏压增加成核(BEN)、两步生长的方法在一氧化碳(CO)和氢气(H2)的环境下制备了金刚石薄膜. 利用扫描电子显微镜(SEM)、Raman光谱仪和透射电子显微镜(TEM)对金刚石薄膜的形貌和结构进行了分析. 研究发现金刚石晶粒在第一步成核及生长的过程中产生了层错和孪晶,而在第二步的生长过程中产生的层错和孪晶很少,最终形成的金刚石晶粒外表面比较光滑,包含有近五次对称或者平行的片状的孪晶,并可以观察到少量的位错. 而在样品的边缘由于等离子体的不均匀产生了比样品中心成核密度低的区域. 在这个区域中,发现了一个新的非金刚石的碳结构. 相似文献
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探讨了脉冲激光诱导液-固界面反应法(PLIR: Pulsed-Iaser Induced Liquid-Solid Interface Reaction )制备金刚石纳米晶的物理化学机制,提出了金刚石纳米晶的成核机理,即由激光诱导石墨六方结构原子团过渡到石墨菱方结构、然后转变成立方金刚石晶核,以及由石墨六方结构直接转变成六方金刚石结构的相变模型,并讨论了基于液-固界面反应的纳米晶生长动力学,较好地从动力学上解释了合成金刚石纳米晶的物理化学机制。 相似文献
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实现金刚石薄膜的异质外延是目前CVD金刚石薄膜制研究的主要奋斗目标,而直流负偏压增强金刚石成核法被认为是达到这一目标的有效途径。文章简要评述了微波等离子体CVD制备金刚石薄膜中的直流负偏压增强成核法,以及由此而发展的直流正偏压增强成核法和叠加交流成分的直流负偏压增强成核法,介绍了它们在异质外延金刚石薄膜中的应用。 相似文献
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利用热丝辅助双偏压氢等离子体对化学气相沉积金刚石薄膜进行了纳米尺度上的表面改装,制造出锥状金刚石列阵.金刚石薄膜内在的柱状结构使氢离子在刻蚀薄膜时产生非均匀的刻蚀速率,对锥状表面的形成起着重要作用.另一方面,溅射出的含碳粒子会发生二次沉积,最终的特征表面形貌取决于刻蚀与含碳基团再沉积之间的相互竞争.栅极的使用影响基底区域放电的伏安特性,改变栅极电流可以对形成的金刚石特征表面结构进行有效调节.在处理过程中少量掺入甲烷,提高了金刚石表面附近的含碳基团浓度,促进二次成核,进而诱发均匀分布的锥状列阵.
关键词:
等离子体
表面
金刚石薄膜 相似文献
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采用新设计的电极结构的等离子体增强化学气相沉积(PECVD)技术,在高功率密度、高氢稀释比、低温、偏压及低反应气压的条件下,在衬底表面形成双等离子流,增加了衬底表面SiC的成核概率,增强成核作用,形成纳米晶.采用高H2等离子体刻蚀弱的、扭曲的、非晶Si—C及Si—Si和Si—H等键时,由于H等离子体对纳米SiC晶粒与非晶态键的差异刻蚀作用,产生自组织生长,发生晶化.Raman光谱和透射电子衍射(TEM)的测试结果表明,纳米晶SiC是4HSiC多型结构.电子显微照片表明平均粒径为16nm,形状为微柱体.实验结果指出,SiC纳米晶的形成必须经过偏压预处理成核,并且其晶化存在一个功率密度阈值;当低于这一功率密度阈值时,晶化消失;当超过这一阈值时,纳米晶含量随功率密度的提高而增加.随着晶化作用的加强,电导率增加.
关键词:
4H-SiC
PECVD
纳米结构
多型薄膜
纳米电子学 相似文献
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单壁碳纳米管在高压下会发生结构相变,导致金属型的碳纳米管变成半导体.相变后碳纳米管中电子的库仑关联的表现形式发生变化,从Luttinger liquid行为转变成环境量子涨落行为.同时,相变后电子波函数的相位关联导致弱局域化行为的出现.为了研究库仑关联和相位关联之间是否有相互影响,使用金刚石对顶砧和液压自锁高压包在0—10 GPa准静压范围内测量了单层碳纳米管样品在低温和不同磁场下的微分电导随偏压的依赖关系.实验结果表明,相位关联和库仑关联是两种独立的效应,各自影响着电子的输运行为.
关键词:
单层碳纳米管
高压
微分电导 相似文献
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提出了金刚石在衬底表面凹缺陷内成核的理论,指出凹缺陷尺度对于金刚石成核有着决定性作用,合适的凹缺陷将使成核率达到最大。并且讨论了该理论对于试图通过控制衬底表面缺陷来控制金刚石成核密度等人工微结构设计研究的意义。 相似文献
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E. M. Malykhin V. A. Krivchenko D. V. Lopaev T. V. Rakhimova S. M. Zyryanov 《Moscow University Physics Bulletin》2011,66(1):54-58
In this work, the structure and chemistry of thin nm-thick carbon films deposited on a substrate using strong 13.5 nm EUV
irradiation under a strong vacuum were studied. The film structure was studied by Raman spectroscopy in comparison with the
Raman spectra of well-known carbon phases: diamond, single-wall nanotubes, nano- and micro-crystalline graphite and amorphous
carbon. As well, FTIR spectroscopy was used to study possible IR-active chemical bonds, primarily, hydrogen bonds. It was
shown that films deposited on a surface under EUV irradiation consists of amorphous sp
2-carbon. The mechanisms of deposition are discussed briefly. Knowledge about the structure and chemistry of such carbon films
is very important for EUV lithography. 相似文献
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The incorporation of hydrogen within ultrananocrystalline diamond/amorphous carbon composite films has been investigated by nuclear reaction analysis (NRA) and Fourier transform infrared spectroscopy (FTIR). The film bulk contains ca. 7.5–8% H (for a deposition temperature of 600 °C), while the H concentration in the surface region is considerably higher. FTIR measurements show that the hydrogen‐rich surface is formed right at the beginning of the deposition process and grows outward as the film thickness increases. It can thus be concluded that surface hydrogen species play an active role in the formation of ultrananocrystalline diamond/amorphous carbon films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Thin polycrystalline, diamond films were prepared by thermal decomposition of hydrocarbon and hydrogen in the presence of a hot tungsten filament (HF CVD technique). Electron Spin Resonance (ESR) spectroscopy investigations were carried out and correlated to diamond microcrystal size estimated on the basis of X-ray diffraction (XRD) measurements. It was shown that both ESR signal and average crystal size of the thin CVD diamond films depend strongly on the ratio of hydrocarbon/hydrogen concentrations in the CVD reactor. XRD spectra indicate the presence of fullerence and, graphitic polytypes in most studied samples, independent of growth conditions. Observed reciprocal proportionality of the ESR signal intensity versus diamond grain size suggests that the above mentioned carbon phases are mainly dispersed at the grain boundaries. 相似文献
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Justyna Kęczkowska 《Central European Journal of Physics》2011,9(2):330-337
The work presents the results of the scanning electron microscopy (SEM) and Raman spectrometry studies of carbonaceous nanostructures
containing nickel nanocrystallites. The films were obtained using a two-step method. In the first phase the Physical Vapour
Deposition (PVD) method was applied, whereas in the second Chemical Vapour Deposition (CVD) method was used. The paper presents
results for samples with various Ni content obtained with different parameters of the two-phase technological process. The
research confirms that the thin films obtained by PVD method contain Ni nanocrystallites distributed in a carbonaceous matrix.
The matrix is composed of various carbon allotropes (amorphous carbon, graphite, fullerene). The thin films made by CVD method
make a matrix when multiwalled, carbonaceous nanotubes are obtained. Depending on the technological process parameters of
each phase, we obtain multiwall nanotubes with a various degree of defects. 相似文献
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A.R. Sobia S. AdnanA. Mukhtiar A.A. KhurramA.A. Turab A. AwaisA. Naveed Q.J. FaisalH. Javaid G.J. Yu 《Current Applied Physics》2012,12(3):712-717
The effect of nitrogen addition in the feed gas on the finally incorporated amount of hydrogen in the diamond nanorods (DNRs) thin films has been investigated. The Raman spectroscopy measurements helped to understand the structural and quality changes with increasing nitrogen gas flow rate during CVD deposition. The hydrogen concentration was measured with 3.0 MeV He2+ beam using elastic recoil detection analysis technique and it was found that with the addition of nitrogen, the hydrogen concentration was increased. The results of non-Rutherford backscattering spectroscopy (NRBS) used to measure the amount of nitrogen in the DNRs thin films have shown that the incorporated nitrogen is below the detection limit of NRBS technique. Our results suggested that the addition of nitrogen has affected the overall quality of diamond films in two ways; increasing the thickness of diamond films by increasing the non-diamond carbon content and increasing the hydrogen impurity incorporation. The role of nitrogen additive on diamond growth and hydrogen incorporation is discussed. 相似文献
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Diamond-like carbon (DLC) films have been deposited using three different
techniques: (a) electron cyclotron resonance---plasma source ion
implantation, (b) low-pressure dielectric barrier discharge, (c)
filtered---pulsed cathodic arc discharge. The surface and mechanical properties of
these films are compared using atomic force microscope-based tests. The experimental results
show that hydrogenated DLC films are covered with soft surface layers
enriched with hydrogen and sp$^{3}$ hybridized carbon while the soft surface
layers of tetrahedral amorphous carbon (ta-C) films have graphite-like
structure. The formation of soft surface layers can be associated with the
surface diffusion and growth induced by the low-energy deposition process.
For typical CVD methods, the atomic hydrogen in the plasmas can contribute
to the formation of hydrogen and sp$^{3}$ hybridized carbon enriched
surface layers. The high-energy ion implantation causes the
rearrangement of atoms beneath the surface layer and leads to an increase in film
density. The ta-C films can be deposited using the medium energy carbon ions
in the highly-ionized plasma. 相似文献
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D. Sarangi C. Godon A. Granier R. Moalic A. Goullet G. Turban O. Chauvet 《Applied Physics A: Materials Science & Processing》2001,73(6):765-768
We report a simple way to synthesize carbon nanotubes and nanostructures from the solid phase. Vacuum annealing of diamond-like
carbon (DLC) films or polyethylene mixed with catalyst in argon atmosphere leads to the formation of nanotubes and nanostructures.
High-resolution transmission electron microscopy studies reveal highly graphitized multi-walled nanotubes (MWNTs) or amorphous
fibre-like structures, depending on the catalyst amount. This synthesis process may give a new approach to understanding the
phase transition of different carbon allotropes into nanotubes or nanostructures.
Received: 3 July 2001 / Accepted: 3 July 2001 / Published online: 2 October 2001 相似文献