非晶含氢碳膜的氧等离子体刻蚀性能研究

用苯作气源,采用电子回旋共振等离子体增强化学气相沉积方法制备了非晶含氢碳膜,并在该系统上用氧等离子体对这些碳膜进行了刻蚀性能的研究.实验中,测量了碳膜在不同氧压强、流量和微波功率下的刻蚀速率,研究了膜的沉积速率与它的刻蚀速率之间的关系.结果表明,膜的刻蚀速率与膜的生长条件密切相关;在低沉积速率下生长的非晶碳膜的刻蚀率低于常用的Novolak光刻胶.这种碳膜具有较强的耐刻蚀性能,可以用作微电子器件制造中的掩膜材料. 关键词：     

新型氧化铝模板自组装制备非晶碳纳米点阵列膜及其场发射性能研究

通过对阳极氧化铝(AAO)模板进行特殊扩孔处理,消除了AAO模板中带电阴离子对沉积碳离子的不良影响,利用磁过滤阴极弧等离子体沉积技术成功制备了非晶碳纳米尖点阵列膜.场发射扫描电镜(FESEM)分析表明,经过氧化和扩孔多步处理制备的AAO模板具有特殊的开口结构,制备的非晶碳纳米尖点阵列完整地复制了AAO模板的孔道阵列结构,纳米点排列整齐有序,直径约100nm,密度达1010cm-2,样品的场发射测试显示,非晶碳纳米点阵列具有良好的电子发射性能,发射电流为10mA/cm-2时的阈值电场为3.7V/μm.     

利用胶体小球掩蔽刻蚀技术制备的半导体纳米阵列的场电子发射特性

利用胶体小球掩蔽刻蚀技术,制备了单晶硅纳米阵列,利用原子力显微镜观察了硅阵列的表面形貌,实验结果表明,硅柱阵列具有高密度和较好的均匀性。同时研究了单晶硅纳米阵列的场电子发射特性。为了提高样品的场发射性能,在所制备的单晶硅有序纳米阵列上生长了一层非晶碳薄膜。与单晶纳米硅柱阵列相比,覆盖有非晶碳膜的样品的场电子发射特性有了明显的改善,表现在场发射的开启电场下降,同时场发射增强因子得到增加。结果表明非晶碳膜确实能够降低电子发射的表面有效势垒,从而增强了场电子发射特性。     

化学气相沉积法制备金刚石膜截面微区Raman分析

采用微区Raman散射分析方法研究化学气相沉积法制备的金刚石膜的横截面.金刚石膜从衬底面到生长面不同位置具有不同特征的Raman谱,依此对膜中的金刚石、石墨和非晶碳成分进行分析.衬底面附近区域对应金刚石膜生长过程的成核阶段,非晶碳成分含量较高,相应于1200—1600cm^-1波段较大的散射强度和存在较强的荧光背底.膜厚增大,非晶碳成分中sp³结构成分首先减少,而sp²结构成分和石墨成分的减少相对缓慢.而生长面附近区域只有比较单纯的晶体金刚石 关键词：     

等离子体增强热丝CVD生长碳纳米尖端的研究

用CH₄，NH₃和H₂为反应气体，利用等离子体增强热丝化学气相沉积系统在不同偏压电流的条件下制备了碳纳米尖端，并用扫描电子显微镜和显微Raman光谱仪对碳纳米尖端进行了研究.结果表明碳纳米尖端是石墨结构，随着偏压电流的增大，碳纳米尖端的顶角减小，生长速率增大.结合有关等离子体和溅射的理论，分析讨论了碳纳米尖端的形成和碳纳米尖端的生长随偏压电流的变化. 关键词： 碳纳米尖端 等离子体 化学气相沉积     

银纳米膜的电化学制备方法及性能表征

采用电沉积方法在表面活性剂与电解液的界面上制备了银纳米膜。通过对甲磺酸银体系和硝酸银体系中纳米银膜的电沉积速率及纳米银膜颗粒进行比较发现，相同条件下硝酸银体系得到的纳米膜晶粒粒径比较小，膜的生长速率较快。选定硝酸银体系为电沉积体系。考察了槽压、电解液的浓度和温度及溶液的pH值对制备银纳米膜的影响，确立了制备银纳米膜的最佳工艺条件为硝酸银浓度5mmol/L，槽压4V，pH3.0,硬脂酸的质量浓度0.2g/L。实验表明，最佳工艺条件下制备的银纳米膜晶粒粒径均匀，平均粒径在20nm左右，近似球形。本方法制备的银纳米膜将在非线性光学材料方面得到应用。     

射频等离子体辅助化学气相沉积方法生长碳纳米洋葱

用射频等离子体辅助化学气相沉积方法生长碳纳米洋葱.电子显微镜观察表明,产物中无碳纳米管等伴随生成,因而制得了较高产率、较高纯度的纳米洋葱.尤其是Co-SiO₂催化剂生长的碳纳米洋葱,实心、光滑,且内无催化剂颗粒,其外层由未闭合的、呈波浪状的石墨片构成,显示出与众不同的微观结构和性能.提出了该方法中碳纳米洋葱的生长机理为碳笼由里向外嵌套形成球形粒子.对波浪状、非闭合结构的形成过程进行了讨论. 关键词： 射频等离子体 化学气相沉积 碳纳米洋葱     

氮对类金刚石薄膜的微观结构内应力与附着力的影响

采用原子力显微镜(AFM)、俄歇电子能谱(AES)和显微压痕分析等手段对射频等离子体增强化学气相沉积法制备的掺氮类金刚石(DLC：N)薄膜的微观结构和力学性能进行了研究.结果表明,随着含氮量的增加,DLC薄膜的AFM表面形貌中出现了几十纳米的颗粒,原子侧向力显微镜和AES分析表明这种纳米颗粒是x大于0.126的非晶氮化碳CN_x结构.这种非晶DLC/CN_x的纳米复合结构,减小了薄膜的内应力,从而提高了薄膜与衬底的附着力. 关键词： 类金刚石碳膜 微观结构 附着特性     

基于钯/碳纳米粒子复合薄膜的双氧水电化学传感性能研究

本文采用团簇束流沉积方法制备了一种复合纳米粒子电化学催化剂,在碳纳米粒子支撑层上沉积钯纳米粒子薄膜,发现其在双氧水电化学传感中具有较高的灵敏度.碳纳米粒子的覆盖率对钯纳米粒子薄膜的双氧水电化学催化活性有明显的影响.当碳纳米粒子覆盖满一个单层的时候,钯/碳纳米粒子复合薄膜对双氧水的检测灵敏度达到了最高值,是没有碳纳米粒子支撑层时的两倍之多.     

a-C:F薄膜的热稳定性与光学带隙的关联

以CF4和C6H6的混合气体作为气源,在微波电子回旋共振化学气相沉积(ECRCVD)装置中制备了氟化非晶碳薄膜(aC:F),并在N2气氛中作了退火处理以考察其热稳定性.通过傅里叶变换红外吸收谱和紫外可见光谱获得了薄膜中CC双键的相对含量和光学带隙,发现膜中CC键含量与光学带隙之间存在着密切的关联,在高微波功率下沉积的氟化非晶碳膜具有低的光学带隙和较好的热稳定性. 关键词： 氟化非晶碳膜 光学带隙 退火温度 热稳定性     

Surface characteristics of Ni catalystic films on growth behavior of multi-walled carbon nanotubes

The effect of the surface characteristics of Ni catalyst films on the growth behavior of multi-walled carbon nanotubes (MWCNTs) were investigated using Ni catalyst films prepared by different physical vapor deposition methods, electron-beam evaporation and sputtering. The growth behavior of MWCNTs was dependent upon the surface roughness of the Ni films. After a pretreatment process with NH₃, the root mean squares of surface roughness of e-beam evaporated and sputtered Ni catalyst films increased to 16.6 and 3.2 nm, respectively. Curled-MWCNTs and carbon-encapsulated Ni nanoparticles were formed on the Ni film deposited by e-beam evaporation while vertically aligned-MWCNTs were grown on the sputter-deposited film. In addition, the surface roughness of the Ni films affected the field emission properties of the MWCNTs. This was considered to originate from the specific growth behavior of the MWCNTs which was primarily caused by the initial surface roughness of the Ni films.     

Characteristics of Carbon Nanotubes Synthesized from Methane and Acetylene in the Presence of a FeCl3 Catalyst

Technical Physics - The structures of carbon nanotubes synthesized by catalytic CVD in the same reactor using different carbon-containing precursors and a FeCl3 catalyst have been compared. Methane...     

Monitoring structural defects and crystallinity of carbon nanotubes in thin films

We report the influence of catalyst formulation and reaction temperature on the formation of carbon nanotube (CNT) thin films by the chemical vapour deposition (CVD) method. Thin films of CNTs were grown on Fe-Mo/Al₂O₃-coated silicon wafer by thermal decomposition of methane at different temperatures ranging from 800 to 1000°C. The electron microscopic investigations, SEM as well as HRTEM, of the as-grown CNT thin films revealed the growth of uniform multi-walled CNTs in abundance. The intensity ratio of D-band to G-band and FWHM of G-band through Raman measurements clearly indicated the dependency of structural defects and crystallinity of CNTs in thin films on the catalyst formulation and CVD growth temperature. The results suggest that thin films of multi-walled CNTs with negligible amount of defects in the nanotube structure and very high crystallinity can be obtained by thermal CVD process at 925°C.     

Effect of nickel,iron and cobalt on growth of aligned carbon nanotubes

The effect of pure nickel, iron and cobalt on growth of aligned carbon nanotubes was systematically studied by plasma-enhanced hot-filament chemical vapor deposition. It is found that the catalyst has a strong effect on the nanotube diameter, growth rate, wall thickness, morphology and microstructure. Ni yields the highest growth rate, largest diameter and thickest wall, whereas Co results in the lowest growth rate, smallest diameter and thinnest wall. The carbon nanotubes catalyzed by Ni have the best alignment and the smoothest and cleanest wall surface, whereas those from Co are covered with amorphous carbon and nanoparticles on the outer surface. The carbon nanotubes produced from Ni catalyst also exhibit a reasonably good graphitization. Therefore, Ni is considered as the most suitable catalyst for growth of aligned carbon nanotubes. Received: 30 November 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002     

Methods for preparation of transparent conductive diamond-like carbon films and mechanisms of conductivity formation

Technology for obtaining transparent conductive diamond-like carbon films has been developed. Conductivity of the films is ensured by doping with nitrogen during the growth process or by preliminary deposition onto the substrate of a catalyst of nanostructure growth. Optical methods of control of the process which allow varying both the transparency and conductivity of the obtained coatings are described. The mechanisms of formation of conductivity in a dielectric carbon matrix were investigated. It is shown that in the presence of catalysts the conductivity of films can be described using a percolation mechanism.     

沉积工艺参数对碳纳米管薄膜场发射性能的影响

利用微波等离子体化学气相沉积(MWPCVD)方法,在不锈钢衬底上直接沉积碳纳米管膜。通过SEM、拉曼光谱和XRD表征,讨论了制备温度和甲烷浓度对碳纳米管膜场发射的影响。结果表明:不同条件下制备的碳纳米管膜的场发射性能有很大差异,保持氢气的流量(100sccm)、生长时间(10min)、反应室压力不变,当甲烷流量为8sccm、温度为700~800℃时,场发射性能最好,开启场强仅为0.8V/μm,发射点分布密集、均匀。     

Synthesis of carbon nanotubes on diamond-like carbon by the hot filament plasma-enhanced chemical vapor deposition method

Carbon nanotubes (CNTs) have attracted considerable attention as possible routes to device miniaturization due to their excellent mechanical, thermal, and electronic properties. These properties show great potential for devices such as field emission displays, transistors, and sensors. The growth of CNTs can be explained by interaction between small carbon patches and the metal catalyst. The metals such as nickel, cobalt, gold, iron, platinum, and palladium are used as the catalysts for the CNT growth. In this study, diamond-like carbon (DLC) was used for CNT growth as a nonmetallic catalyst layer. DLC films were deposited by a radio frequency (RF) plasma-enhanced chemical vapor deposition (RF-PECVD) method with a mixture of methane and hydrogen gases. CNTs were synthesized by a hot filament plasma-enhanced chemical vapor deposition (HF-PECVD) method with ammonia (NH₃) as a pretreatment gas and acetylene (C₂H₂) as a carbon source gas. The grown CNTs and the pretreated DLC films were observed using field emission scanning electron microscopy (FE-SEM) measurement, and the structure of the grown CNTs was analyzed by high resolution transmission scanning electron microscopy (HR-TEM). Also, using energy dispersive spectroscopy (EDS) measurement, we confirmed that only the carbon component remained on the substrate.     

Fabrication of aligned carbon nanotubes on Cu catalyst by dc plasma-enhanced catalytic decomposition

Aligned multi-walled carbon nanotubes (ACNTs) are deposited using copper (Cu) catalyst on Chromium (Cr)-coated substrate by plasma-enhanced chemical vapor deposition at temperature of 700 °C. Acetylene gas has been used as the carbon source while ammonia is used for diluting and etching. The thicknesses of Cu films on Cr-coated Si (100) substrates are controlled by deposition time of magnetron sputtering. The growth behaviors and quality of ACNTs are investigated by scanning electron microscopy (SEM) and transmission electron microscopy. The different performance of ACNTs on various Cu films is explained by referring to the graphitic order as detected by Raman spectroscopy. The results indicate that the ACNTs are formed in tip-growth model where Cu is used as a novel catalyst, and the thickness of Cu films is responsible to the diameter and quality of synthesized CNTs.     

金镍复合膜上碳纳米管的定向生长及生长过程中金的作用

以金镍复合膜作催化剂，在96%的高氢气浓度下实现了碳纳米管的定向生长，并对其生长过 程进行了深入探讨.结果表明，高氢气浓度下碳纳米管生长的实现与本实验所选用的催化剂 ——金镍复合膜有密切关系.催化剂中金的参与，促进了碳在催化剂中的扩散，提高了碳在 催化剂中的活度.与催化剂中没有金的情况相比较，金的参与有利于镍吸收气氛中的碳，从 而使镍更容易达到碳饱和，有利于在高的氢气浓度下实现碳纳米管的定向生长. 关键词： 金镍复合膜 高氢气浓度 原子氢 碳活度     

Growth and field emission property of coiled carbon nanostructure using copper as catalyst

Coiled carbon nanostructure (CNS) is prepared by a catalytic chemical vapor deposition (CVD) process on copper/chromium films deposited by radio frequency (RF) sputtering. Uniform CNS with coiled structure is fabricated by changing the size of the catalyst particles. The effects of Cu catalyst size and RF sputtering power, on the growth of the coiled CNS are discussed, and the results importantly conclude that Cu-catalyzed CVD offers a preferable control of coiled CNS to optimize the field emission property for application.