白碳纳米晶薄膜及其场致电子发射特性

利用微波等离子体化学气相沉积方法,以甲烷、氢混合气体为反应气体,具有钛镀层的玻璃作为衬底,制备了具有sp¹杂化结构的白碳纳米晶薄膜。利用X射线衍射、俄歇电子能谱,以及扫描电子显微镜对薄膜结构进行了表征。以白碳纳米晶薄膜为阴极,以镀有ITO透明导电薄膜玻璃为阳极,采用二极管结构,测试了白碳纳米晶薄膜的场致电子发射特性。开启电场为2.5 V/μm,在电场为5 V/μm时的电流密度为200μA/cm²。对白碳纳米晶薄膜生长机理,以及其场致电子发射机制进行了讨论。     

脉冲激光晶化超薄非晶硅膜的分子动力学研究

利用准分子脉冲激光晶化非晶硅薄膜是制备高密度尺寸可控的硅基纳米结构的有效方法之一.本文将脉冲激光对非晶硅超薄膜的影响处理为热传导问题,采用了基于Tersoff势函数的分子动力学方法模拟了在非晶氮化硅衬底上2.7 nm超薄非晶硅膜的脉冲激光晶化过程.研究了不同激光能量对非晶硅薄膜晶化形成纳米硅的影响,发现在合适的激光能量窗口下,可以获得高密度尺寸可控的纳米硅薄膜,进而模拟了在此能量作用下非晶硅膜中成核与生长的机理与微观过程,并对晶化所获得的纳米硅薄膜的微结构进行了分析. 关键词： 非晶硅 分子动力学 脉冲激光晶化     

激光诱导铝基碳纳米管薄膜及场发射性能

结合电泳沉积和激光纳米焊接技术在常温下成功制备了铝基单壁碳纳米管(SWCNTs-Al)薄膜。首先,将单壁碳纳米管电泳沉积到铝片基底上,再使用皮秒脉冲激光构建二者的可靠连接。对SWCNTsAl薄膜进行场发射性能测试,开启电压从焊接前的5.1V/μm降低到2.1V/μm,发射电流密度显著提高且更加稳定。这主要是激光纳米焊接后界面接触阻抗减小,场致电子发射更容易实现的结果。基于SWCNTs-Al薄膜的表面形貌图和场发射性能测试结果,确定了最优的激光纳米焊接参数。     

类富勒烯纳米晶CNx薄膜及其场致电子发射特性

利用微波等离子体增强化学气相沉积技术制备出了CN_x薄膜,并利用x射线光电子能谱、x射线衍射、扫描电子显微镜和Raman光谱等测试手段对所制备的CN_x薄膜的微结构和成分进行了分析.研究了其场致电子发射特性.发现薄膜的结构和场发射特性与反应系中的甲烷、氮气及氢气的流量比有关,当甲烷、氢气及氮气流量比为8/50/50 sccm时,制备的薄膜具有弯曲层状的纳米石墨晶体结构（类富勒烯结构）和很好的场发射特性.场发射阈值电场降低至1.1V/μm.当电场为5.9V/μm时,平 关键词： 类富勒烯 x薄膜')" href="#">CN_x薄膜 场致电子发射 微波等离子体增强化学气相沉积     

纳米金刚石掺混纳米氧化锌的场发射特性

利用水热法制备了菊花状的氧化锌纳米棒,并进行表征,将纳米氧化锌掺入纳米金刚石中配制成电泳液,超声分散后电泳沉积到钛衬底上,再经热处理后进行场发射特性的测试.结果表明:未掺混的金刚石阴极样品的开启电场为7.3V/μm,在20V/μm的电场下,场发射电流密度为81μA/cm2;掺混后阴极样品的场发射开启电场降低到4.7~6.0V/μm,在20V/μm电场下,场发射电流密度提高到140~158μA/cm2.原因是纳米ZnO掺入后,增强了涂层的电子输运能力、增加了有效发射体数目,提高了场增强因子β,而金刚石保证了热处理后涂层与衬底的良好键合,形成了欧姆接触,降低了场发射电流的热效应.场发射电流的稳定性随掺混ZnO量的增加而下降,要兼顾场发射电流密度及其稳定性,适量掺入ZnO可有效提高纳米金刚石的场发射性能.     

非晶金刚石薄膜的场致电子发射性能研究

利用真空磁过滤弧沉积技术制备出一种高sp³含量的非晶碳膜———非晶金刚石薄膜，并对这种非晶金刚石薄膜的场电子发射特性及其发射机理进行了研究．实验结果表明，在阈值电场低于20V/μm情况下，得到的场发射电流达20—40μA，薄膜的电子发射行为符合Fowler-Nordheim场发射理论．研究表明，这种非晶金刚石薄膜具有负的电子亲合势和较小的有效功函数以及相对较低的禁带宽度 关键词：     

类球状微米金刚石聚晶的场发射

在覆盖金属钛层的陶瓷上,采用微波等离子体化学气相沉积(MPCVD)法制备出类球状微米金刚石聚晶薄膜。利用扫描电子显微镜、拉曼光谱,X射线衍射,分析了薄膜的结构和表面形貌。测试了类球状微米金刚石聚晶膜的场致电子发射特性。开启电场仅为0.55V/μm,在2.18V/μm的电场下,其场发射电流密度高达11mA/cm2。仔细分析了膜的发射过程,发现类球状微米金刚石聚晶的结构对发射有很大影响,并对其发射机理进行了研究。     

类富勒烯纳米晶CNx薄膜及其场致电子发射特性

利用微波等离子体增强化学气相沉积技术制备出了CNx薄膜,并利用x射线光电子能谱、x射线衍射、扫描电子显微镜和Raman光谱等测试手段对所制备的CNx薄膜的微结构和成分进行了分析.研究了其场致电子发射特性.发现薄膜的结构和场发射特性与反应系中的甲烷、氮气及氢气的流量比有关,当甲烷、氢气及氮气流量比为8/50/50sccm时,制备的薄膜具有弯曲层状的纳米石墨晶体结构(类富勒烯结构)和很好的场发射特性.场发射阈值电场降低至1.1V/μm.当电场为5.9V/μm时,平均电流密度达70μA/cm2,发射点密度大于1×104cm-2.     

多层纳米AlGaN薄膜制备及其场发射性能

本文采用激光脉冲沉积系统在SiC基底上制备了GaN/AlN/GaN多层纳米结构薄膜,探索了多层纳米薄膜量子结构增强场发射性能.X射线衍射和扫描电子显微镜结果表明,已成功制备出了界面清晰、结晶良好的GaN/AlN/GaN多层纳米薄膜.场发射测试结果表明:多层纳米薄膜结构相对于GaN和AlN单层纳米薄膜,其场发射性能得到显著提升.其开启电场低至0.93V/μm,电流密度在5.5V/μm时已经能够达到30mA/cm~2.随后进一步分析了纳米结构增强场发射机理,电子在GaN/AlN/GaN多层纳米薄膜结构中的量子阱中积累使其表面势垒高度显著下降,并通过共振隧穿效应进一步提高电子的透过概率,从而使场发射性能极大提高.研究结果将为应用于高性能场发射器件的纳米薄膜材料的制备提供一种好的技术方案.     

ZnO纳米棒的低温溶液法制备、光电特性研究及其在有机/无机复合电致发光中的应用

利用水热法制备了垂直于衬底的定向生长的ZnO纳米棒,利用扫描电子显微镜及光致发光的方法对其形貌及光学特性进行了表征,利用场发射性能测试装置对ZnO纳米棒的场发射性能进行了测试.结果表明:利用水热法在较低的温度(95 ℃) 下生长了具有较好形貌和结构的ZnO纳米棒,并表现出了较好的场发射特性,当电流密度为1 μA/cm²时,开启电场是2.8 V/μm,当电场为6.4 V/μm时,电流密度可以达到0.67 mA/cm²,场增强因子为3360.稳定性测试表明,在5 h内,4.5 V/μm的电场下,其波动不超过25%.将制备的ZnO纳米棒应用到有机/无机电致发光中,其中ZnO纳米棒为电子传输层,m-MTDATA(4,4',4″-tris{N,(3-methylphenyl)-N-phenylamino}-triphenylamine) 为空穴传输层,得到了ZnO的342 nm的紫外电致发光,此发光较ZnO纳米棒光致发光的紫外发射有约40 nm的蓝移. 关键词： ZnO纳米棒 场发射 水热法 有机/无机复合电致发光     

Enhanced electron field emission from dense Si nano-dots prepared by laser crystallization of ultrathin amorphous Si films

Dense Si nano-dots with a surface area density of >10¹⁰ cm^?2 were fabricated by excimer laser induced crystallization of 15 nm-thick amorphous Si thin films. The enhanced electron field emission characteristics were found from laser irradiated samples. The threshold electric field is as low as 9.8V/μm and the field enhancement factor can reach as large as 719, which is compatible with the other good cold cathode materials. The improvements in field emission behavior can be associated with the change in the surface morphology after laser irradiation as well as the enhanced internal electric field due to the formation of Si nano-dots within the films.     

InN纳米线的低压化学气相沉积及其场发射特性研究

利用低压化学气相沉积方法在以Au作催化剂的Si衬底上生长了InN纳米线. 扫描电子显微镜分析表明，这些纳米线的直径在60—100 nm的范围内, 而其长度大于1 μm.高分辨透射电子显微镜图像表明，合成的纳米线中含有六方相和立方相的InN晶体.这些InN纳米线具有良好的场发射特性和稳定的场发射电流，其开启场为10.02 V/μm(电流密度为10 μA/cm²)，在24 V/μm 的电场下，其电流密度达到5.5 mA/cm².此外，对InN纳米线的场发射机理也进行了讨论. 关键词： InN纳米线 场电子发射 非线性Fower-Nordheim曲线     

Enhanced field emission from Si doped nanocrystalline AlN thin films

Si doped and undoped nanocrystalline aluminum nitride thin films were deposited on various substrates by direct current sputtering technique. X-ray diffraction analysis confirmed the formation of phase pure hexagonal aluminum nitride with a single peak corresponding to (1 0 0) reflection of AlN with lattice constants, a = 0.3114 nm and c = 0.4986 nm. Energy dispersive analysis of X-rays confirmed the presence of Si in the doped AlN films. Atomic force microscopic studies showed that the average particle size of the film prepared at substrate temperature 200 °C was 9.5 nm, but when 5 at.% Si was incorporated the average particle size increased to ∼21 nm. Field emission study indicated that, with increasing Si doping concentration, the emission characteristics have been improved. The turn-on field (E_to) was 15.0 (±0.7) V/μm, 8.0 (±0.4) V/μm and 7.8 (±0.5) V/μm for undoped, 3 at.% and 5 at.% Si doped AlN films respectively and the maximum current density of 0.27 μA/cm² has been observed for 5 at.% Si doped nanocrystalline AlN film. It was also found that the dielectric properties were highly dependent on Si doping.     

类金刚石和碳氮薄膜的电化学沉积及其场发射性能研究

利用电化学方法在室温下成功地沉积了类金刚石(DLC)薄膜和非晶CN_x薄膜，并 对制备条件进行了讨论.通过扫描电子显微镜、傅里叶变换红外光谱技术，分析了薄膜的表面形貌和化学结合状态.场发射测量结果表明：DLC膜和非晶CN_x的开启场分别为88和 10V/μm；并且在23V/μm的电场下，DLC膜和非晶CN_x膜的发射电流密度分别达到10 和037mA/cm². 关键词： 电化学沉积 类金刚石薄膜 x薄膜')" href="#">CN_x薄膜 场致电子发射     

Preparation and field emission properties of carbon nanotubes cold cathode using melting Ag nano-particles as binder

A new preparation process for carbon nanotubes (CNTs) cold cathode was studied through the replacement of traditional organic or inorganic binder with Ag nano-particles. This method has the advantages of low preparation temperature and fine electrical contact between CNTs paste and substrate. A mixture paste of CNTs, Ag nano-particles and other organic solvents was spreaded on Si substrate. By melting and connecting of Ag nano-particles after sintered 30 min at 250 °C, a flat CNTs films with good field emission properties was obtained. The measurements reveal that the turn on electric field and the threshold electric field of as-prepared CNTs cathode are 2.1 and 3.9 V/μm respectively and the field emission current density is up to 41 mA/cm² at an applied electric field of 4.7 V/μm.     

Field emission from a-GaN films deposited on Si (100)

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.     

Enhanced field emission from ZnO nanopencils by using pyramidal Si(1 0 0) substrates

Zinc oxide nanopencil arrays were synthesized on pyramidal Si(1 0 0) substrates via a simple thermal evaporation method. Their field emission properties have been investigated: the turn-on electric field (at the current density of 10 μA/cm²) was about 3.8 V/μm, and the threshold electric field (at the current density of 1 mA/cm²) was 5.8 V/μm. Compared with similar structures grown on flat Si substrates, which were made as references, the pyramidal Si-based ZnO nanopencil arrays appeared to be superior in field emission performance, thus the importance of the non-flat substrates has been accentuated. The pyramidal Si substrates could not only suppress the field screening effect but also improve the field enhancement effect during the field emission process. These findings indicated that using non-flat substrates is an efficient strategy to improve the field emission properties.     

Field electron emission from HfNxOy thin films deposited by direct current sputtering

HfN_xO_y thin films were deposited on Si substrates by direct current sputtering at room temperature. The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). SEM indicates that the film is composed of nanoparticles. AFM indicates that there are no sharp protrusions on the surface of the film. XRD pattern shows that the films are amorphous. The field electron emission properties of the film were also characterized. The turn-on electric field is about 14 V/μm at the current density of 10 μA/cm², and at the electric field of 24 V/μm, the current density is up to 1 mA/cm². The field electron emission mechanism of the HfN_xO_y thin film is also discussed.     

Synthesis and field emission properties of GaN nanowires

Gallium nitride (GaN) nanowires grown on nickel-coated n-type Si (1 0 0) substrates have been synthesized using chemical vapor deposition (CVD), and the field emission properties of GaN nanowires have been studied. The results show that (1) the grown GaN nanowires, which have diameters in the range of 50-100 nm and lengths of several micrometers, are uniformly distributed on Si substrates. The characteristics of the grown GaN nanowires have been investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM), and through these investigations it was found that the GaN nanowires are of a good crystalline quality (2) When the emission current density is 100 μA/cm², the necessary electric field is an open electric field of around 9.1 V/μm (at room temperature). The field enhancement factor is ∼730. The field emission properties of GaN nanowires films are related both to the surface roughness and the density of the nanowires in the film.