共查询到20条相似文献,搜索用时 93 毫秒
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利用改造的扫描电子显微镜(SEM)设备,在SEM腔体中利用钨(W)探针测试了单颗粒金刚石的I-V与场发射特性,结果表明结晶良好的金刚石的I-V特性服从欧姆定律,而孤立的菜花状金刚石颗粒(cauliflower-like diamond)的I-V特性基本符合Pool-Frenkel输运特性.场发射特性表明,结晶良好的金刚石薄膜基本没有场发射,而孤立的菜花状的金刚石颗粒具有一定的场发射.CVD金刚石的场发射过程中,缺陷对电子的输运起主导作用. 相似文献
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采用液相电化学沉积技术制备了ZnO纳米颗粒掺杂的类金刚石(DLC)薄膜, 研究了ZnO纳米颗粒掺杂对DLC薄膜场发射性能的影响. 利用X射线光电子能谱、透射电子显微镜、Raman光谱以及原子力显微镜分别对薄膜的化学组成、 微观结构和表面形貌进行了表征. 结果表明: 薄膜中的ZnO纳米颗粒具有纤锌矿结构, 其含量随着电解液中Zn源的增加而增加. ZnO纳米颗粒掺杂增强了DLC薄膜的石墨化和表面粗糙度. 场发射测试表明, ZnO纳米颗粒掺杂能提高DLC薄膜的场发射性能, 其中Zn与Zn+C的原子比为10.3%的样品在外加电场强度为20.7 V/μm时电流密度达到了1 mA/cm2. 薄膜场发射性能的提高归因于ZnO掺杂引起的表面粗糙度和DLC薄膜石墨化程度的增加. 相似文献
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目前,金刚石的合成主要是以石墨为原料,采用高温高压法合成金刚石小颗粒.尽管从五十年代起,许多研究工作者以碳氢化合物为原料想在低气压下合成金刚石薄膜.但一直到七十年代初,S.Aissenbera[1]和C·Weissma-netl[2]等才用离子淀积法生长出了类金刚石薄膜(即膜的大部分为非晶碳结构). 八十年代以来,B.V.Spitsyn[3]提出的化学输运法,S.Matsumoto[4]提出的热丝化学气相淀积(CVD)法,Mutsukazu Kamo[5]等提出的微波等离子体CVD法和A.Sawabe[6]提出的电子促进CVD法,都是以碳氢化合物为原料,混合大量氢气,才生长出真正的金刚石颗粒和薄膜.… 相似文献
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利用热丝化学气相沉积法研究了氮气浓度对金刚石薄膜成核和生长的影响.实验发现氮气的 加入对金刚石成核密度影响不大,但促进了已形成的金刚石核的长大.适量的氮气不仅使金 刚石生长速率得到很大的提高,而且稳定了金刚石薄膜(100)面的生长,使金刚石薄膜具有 更好的(100)织构.利用原位光发射谱对衬底附近的化学基团进行了研究.研究表明,氮气的 引入使得金刚石生长的气相化学和表面化学性质发生了很大变化.含氮基团的萃取作用提高 了金刚石表面氢原子的脱附速率,从而提高了金刚石膜的生长速率.而含氮基团的选择吸附 使金刚石
关键词:
氮气
金刚石薄膜
织构
原位光发射谱 相似文献
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Pankaj M. KoinkarSandip S. Patil Tae-Gyu KimDaisuke Yonekura Mahendra A. More Dilip S. JoagRi-ichi Murakami 《Applied Surface Science》2011,257(6):1854-1858
Boron doped diamond films were synthesized on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) technique. The effect of B2O3 concentration varied from 1000 to 5000 ppm on the field emission characteristics was examined. The surface morphology and quality of films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. The surface morphology obtained by SEM showed variation from facetted microcrystal covered with nanometric grains to cauliflower of nanocrystalline diamond (NCD) particles with increasing B2O3 concentration. The Raman spectra confirm the formation of NCD films. The field emission properties of NCD films were observed to improve upon increasing boron concentration. The values of the onset field and threshold field are observed to be as low as 0.36 and 0.08 V/μm, respectively. The field emission current stability investigated at the preset value of ∼1 μA is observed to be good, in each case. The enhanced field emission properties are attributed to the better electrical conductivity coupled with the nanometric features of the diamond films. 相似文献
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A comparative study of field emission properties of carbon nanotube films prepared by vacuum filtration and screen-printing 总被引:1,自引:0,他引:1
A comprehensive comparative study of electron field emission properties of carbon nanotube (CNT) films prepared by vacuum filtration and screen-printing was carried out. Field emission performance of vacuum filtered CNT films with different filtered CNT suspension volumes was systematically studied, and the optimum electron emission was obtained with a low turn on field of ∼0.93 V/μm (at 1 μA/cm2) and a high field enhancement factor β of ∼9720. Comparing with screen-printed CNT films, vacuum filtered CNT films showed better electron emission performance, longer lifetime, and greater adhesive strength to substrates. This work reveals a potential use of vacuum filtered CNT films as field emission cathodes. 相似文献
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Amorphous gallium nitride (a-GaN) films have been deposited on Si (100) substrates using ion-assisted deposition. The deposited films were characterised by X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD confirms the amorphous nature of the films and AFM showed nanostructures in the films. The field electron emission from the film was obtained in a probe-hole field emission microscope, and the current-voltage (I-V) characteristics were studied. The corresponding Fowler-Nordheim (F-N) plots showed a linear behaviour. A current density of 0.1 A/cm2 has been obtained for 1.2 V/μm electric field. The field emission current-time (I-t), curves were recorded at a current level of 500 nA for 3 h. The field emission behaviour is compared with that of crystalline GaN as reported in literature. 相似文献
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The effects of Ar microwave plasma treatment on field emission properties of the printed carbon nanotubes (CNTs) cathode films using Ag nano-particles as binder were investigated. The field emission J-E characteristics were measured at varied plasma treatment time. Significant improvement in emission current density, emission stability and uniformity were achieved for the Ar treated CNTs films, even though the plasma treatment increased the turn on electric field slightly. High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy revealed the microstructural changes of CNTs after the plasma treatment. The improved field emission properties of CNTs film can be attributed to the generation of a high density of structural defects after treatment, which increased greatly the possible emission active sites. Besides, the formation of the sharpened and open-ended CNTs tips is all helpful for improving the field emission properties of the treated CNTs. 相似文献
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R. Maity S. Das M.K. Mitra K.K. Chattopadhyay 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):605-612
Zinc oxide (ZnO) nano/microfibrous thin films were successfully synthesized by a catalyst free solution route on glass and Si substrates. X-ray diffraction study revealed the formation of ZnO nanofibers of hexagonal crystalline structure. The texture coefficient of different planes varied with annealing temperature and that of the (0 0 2) plane was the highest for films annealed at temperature 873 K. Scanning electron micrograph showed the well formation of ZnO nano/microfibers with an average diameter 500 nm and having an average aspect ratio 150. UV–Vis–NIR spectroscopic study for the films deposited on glass substrates showed the high transmittance in the visible and near-infrared region. It was also observed that the band gap energy decreased as the films were annealed at higher temperature. The band gap energies of nanostructured ZnO thin films were determined to be in the range 3.03–3.61 eV. The photoluminescence study showed an UV emission peak at 397 nm, a visible blue–green emission peak at 468 nm and a green emission peak at 495 nm. Field emission properties of nanofiber ZnO thin film showed considerably low turn-on field around 1.4 V/μm. The emission current was as high as 70 μA at the field of 3.6 V/μm. 相似文献
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《Current Applied Physics》2005,5(4):387-391
Using a RF magnetron sputtering, amorphous carbon (a-C) and N-doped a-C (a-C:N) thin films were fabricated as field electron emitter. These thin films were deposited on Si(0 0 1) substrate at several temperatures. The field emission property was improved for a-C thin films grown at higher substrate temperatures. Furthermore, a-C:N film exhibits field emission property better than that of undoped a-C film. These results are explained in terms of the change in surface morphology and structural properties of a-C film. 相似文献
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掺杂对碳纳米管拉曼光谱及场发射性能的影响 总被引:3,自引:0,他引:3
采用高温热解法在860℃分别制备出了镓、氮以及硼和氮掺杂的碳纳米管,提纯后利用丝网印刷工艺分别将它们制备成薄膜,并测试了它们的拉曼光谱与场发射性能。测试结果表明,掺杂纳米管的缺陷密集度比纯碳纳米管明显增大,而它们的场致电子发射性能则与掺杂元素的性质密切相关。镓和氮掺杂的纳米管均具有非常优异的场发射性能,而硼和氮共掺杂的纳米管的场发射性能很差。掺杂引起碳纳米管费米能级附近能态密度的变化及功函数的降低是其具有优异场致电子发射性能的主要原因。 相似文献
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Columnar growth of crystalline silicon films on aluminium-coated glass by inductively coupled plasma CVD at room temperature 下载免费PDF全文
Silicon films were grown on aluminium-coated glass by inductively
coupled plasma CVD at room temperature using a mixture of SiH4
and H2 as the source gas. The microstructure of the films was
evaluated using Raman spectroscopy, scanning electron microscopy and
atomic force microscopy. It was found that the films are composed of
columnar grains and their surfaces show a random and uniform
distribution of silicon nanocones. Such a microstructure is highly
advantageous to the application of the films in solar cells and
electron emission devices. Field electron emission measurement of
the films demonstrated that the threshold field strength is as low
as ~9.8V/μm and the electron emission characteristic is
reproducible. In addition, a mechanism is suggested for the columnar
growth of crystalline silicon films on aluminium-coated glass at room
temperature. 相似文献
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X.M. Cai F. Ye E.Q. Xie D.P. Zhang P. Fan 《Applied Physics A: Materials Science & Processing》2008,90(3):555-558
HfNxOy thin films were deposited on Si substrates by direct-current sputtering. The influence of N2 ambient annealing on the morphology, structure and field emission properties of the HfNxOy thin films was studied systematically. Scanning electron microscopy indicates that both the as-deposited and the annealed
films are composed of nanoparticles, and the particle sizes of these films do not change much before and after annealing.
Atomic force microscopy shows that the surface of the as-deposited films is smooth while that of the annealed films becomes
rough, with many protrusions. X-ray diffraction patterns demonstrate that the as-deposited films are amorphous while the samples
annealed at over 500 °C are polycrystalline. It is found that the field electron emission properties of the annealed films
are better than those of the as-deposited films. The film annealed at 800 °C shows the best field emission properties. The
mechanism for the improvement of the field electron emission property of the annealed thin films is also discussed.
PACS 73.61.-r; 79.70.+q; 81.05.-t 相似文献