石墨烯在场发射器件中的应用与研究现状

场电子发射是一种独特的量子隧穿效应,也是真空微电子学的基础之一。基于场发射技术的冷阴极发射体一直被视为未来理想的电子发射阴极。石墨烯是一种具备单层碳原子结构的新型碳材料,其电子迁移率高、机械强度高、热导率高,具有稳定的物理化学特性,因此受到科研工作者的广泛关注。与此同时石墨烯具有较高的长径比(横向尺寸与厚度的比值),这一结构特性能够获得较大的场增强因子。石墨烯的上述特性使得其成为具有广阔应用前景的场发射阴极。本文主要综述石墨烯场发射理论的研究进展、石墨烯/石墨烯基场发射阴极的研究现状、场发射阴极结构以及场发射阴极的制备方法,并对场发射领域的石墨烯研究进行了展望。     

场致发射电子源的应用及其研究进展

由于具有低温、电子瞬间发射等优势,场致发射电子源在X射线管、负氢离子源、显示器件等领域都具有应用潜力。本文首先介绍了场致发射的几种应用;比较分析了不同场致发射电子源及其特点;最后结合实验研究工作,分析了类金刚石膜作为场致发射阴极材料的可行性。分析可知:Spindt加工困难且易于损坏;碳纳米管以其独特的结构成为目前研究最热的材料;类金刚石膜易于合成、成份可调节,它兼具的金刚石和石墨的优点使其成为一种潜在的理想场致发射阴极材料。     

碳基场发射冷阴极材料的研究

场发射冷阴极材料作为真空微电子器件的核心部件,在真空微电子场发射的研究与应用中占有极其重要的地位.目前碳基材料金刚石、类金刚石和碳纳米管在场发射冷阴级的研究中居统治地位.阐述了以上3种材料的制备工艺,发射特性,提出了改进其发射性能的措施,并对它们目前存在的问题及其应用前景进行了展望.     

应用于场致发射的掺杂纳米金刚石膜的研究

场致发射是一种新型显示技术,具有良好应用前景,场发射显示器的核心内容是场发射阴极材料,纳米金刚石由于低表面粗糙度、低场发射强度、高发射电流密度、大比表面积、网状结构以及高密度悬挂键等优秀电化学性能成为场发射的理想阴极材料.本文阐述了化学气相沉积法制备纳米金刚石薄膜的沉积装置、预处理和工艺参数,并介绍了金刚石掺杂机理和掺入元素的研究现状.     

磁过滤阴极真空弧法制备类金刚石膜的场致发射特性研究

采用磁过滤阴极真空弧沉积法,在Cu基底表面上制备了以钛(Ti)和碳化碳(TiC)作为过滤层的类金刚石膜层。利用自制的场致发射特性测试设备,研究了类金刚石膜层的场致发射特性。利用拉曼光谱仪(Raman)和扫描电子显微镜(SEM)等分析方法对类金刚石膜的键合结构和微观形貌进行了表征。研究发现,利用磁过滤阴极真空弧沉积法可以在沉积温度100℃下制备膜基结合力较好的类金刚石膜。沉积速率为15 nm/min。类金刚石膜具有较好的场致发射特性,开启电压约为40 V/μm。Raman分析得到不同基底偏压下的类金刚石膜的I_D/I_G为1.19～1.57;SEM分析显示薄膜的微观结构上具有微米级突起结构。实验表明,应用磁过滤阴极真空弧方法可以制备出高sp~3含量、表面具有微米级突起的类金刚石膜,这种类金刚石膜具有有利于场致发射的特性。     

氢等离子体处理对类金刚石膜场发射性能的影响

采用大功率、高重复频率、准分子激光溅射热解石墨靶制备了类金刚石膜,研究了直流辉光氢等离子体处理对类金刚石膜的场发射性能的影响。结果表明:氢等离子体处理后,类金刚石膜的场发射性能明显提高,其发射阈值电场由26V/μm下降到19V/μm。氢等离子体刻蚀除去了类金刚石膜生长表面的富含石墨的薄层,露出的新表面具有较低的功函数;膜表面的悬键被氢原子饱和,进一步降低了电子亲和势,改善了膜的场发射性能。     

类金刚石膜用作负氢离子表面转化材料的可行性分析

负氢离子源已经成为核聚变装置中性束注入加热系统的首选离子源,优异的负氢离子表面转化材料是其中的关键。金刚石膜具有的负的电子亲合势使其具有优异的二次电子发射性能,进而使其成为可能的负氢离子源表面转化材料。在本论文中,介绍了负氢离子源的结构、工作过程和工作模式,在总结金刚石膜的二次电子发射理论和提高金刚石膜二次电子发射性能的方法的基础上,分析了类金刚石膜成为负氢离子表面转化材料的可行性:类金刚石膜以其同时具有的金刚石相和石墨相,兼具良好导电性和优异电子发射性能。在未来的负氢离子源中,类金刚石膜可能会成为用于负氢离子表面转化的优异可选材料。     

阴极电弧法定向生长的铜纳米线上沉积非晶碳膜及其场发射特性

以阴极电弧法,分别于硅基材与铜纳米线(CuNWs)/硅基材(其中铜纳米线系阳极氧化铝(AAO)模板技术成长于硅基材上)沉积非晶碳膜,,分别以扫描电子显微镜(SEM)、原子力电子显微镜(AFM)和X光电子光谱仪(XPS)表征了非晶碳膜/铜纳米线/硅基材与非品碳膜/硅基材两者之表面形貌、粗糙度、结构及键结等物理特性.并比较两者之电子场发射特性.研究结果显示:两者都拥有低起始电场及高电流密度,其中非品碳膜/铜纳米线/硅基材的场发射起始电压为3.75 V/μm优于非品碳膜/硅基材的15 V/μm,因此非晶碳膜/铜纳米线/硅基材更适用于场发射平面显示器(FED)之发射子,可应用于高稳定性及低成本之场发射平面显示器之研发.     

多晶金刚石锥状场发射阵列冷阴极研究

本文报导了一种新型金刚石场发射阵列冷阴极的制造方法和电子发射性能，通过数据分析得到了这种金刚石发射体的有效表面功函数和总有效发射面积。并与用其它方法获得的几种膜的发射性能作了比较。测量结果表明，这是一种很有应用潜力的制造方法。     

场致电子发射薄膜材料研究评述

场致电子发射(场发射)薄膜材料由于在场发射平板显示器、电子源等诸多高性能真空微电子器件上具有广阔的应用前景,引起了人们广泛的关注与研究兴趣.综述了场发射薄膜材料的理论与实验研究进展,并评述了场致电子发射薄膜材料研究的瓶颈问题及未来发展方向与趋势.     

Ferroelectric emission studies for electron emission lithography applications

Ferroelectric switching emission, dielectric switching emission, and pyroelectric emission were studied by patterning images on electron resist for electron emission lithography applications. It was observed that the pyroelectric emission is most acceptable for a high throughput 1:1 electron projection lithography application. A 1:1 electron projection lithography was demonstrated by patterning images with line widths of 30 /spl mu/m and using pyroelectric emission. A degradation of the pyroelectric emission property of the material was observed during repeated heating cycles below the phase-transition temperature of the ferroelectric material. Annealing excursions above the phase transition temperature prevented the degradation of the pyroelectric emitter.     

Effect of beam-splitter emission in Fourier-transform emission spectroscopy

A simple model of an emission Fourier-transform spectrometer is provided for a beam splitter with infinitesimal thickness but with general optical properties otherwise. Using the principle of conservation of energy, we derived the rigorous expressions that relate the interferograms from three different signals (source, reference, and beam-splitter emission), which are simultaneously observed by the detector. The relationship among phase and amplitude of the three interferograms is evaluated. The results indicate that the behavior of a Fourier-transform emission spectrometer may be more complicated than what is assumed in some models. Calibration procedures should reflect the implications of this rigorous approach.     

Vibroelectronic emission

A newly discovered effect in which electrons are emitted from a vibrating silver-oxygen-cesium photocathode is described. Pis’ma Zh. Tekh. Fiz. 24, 65–69 (December 12, 1998)     

碳纳米管场发射阴极的制备及其场发射特性

采用电泳法将碳纳米管组装到电化学淀积的银台阵列上作为场发射阴极并研究了它的场发射特性.场发射特性测试结果表明:该阴极具有优异的场发射特性,开启电场为2.8V/μm,在应用电场为5.5V/μm时,发射电流密度达到1.7mA/cm2.具有优异的发射性能的原因可以归结到银台的边缘和银台类山状的表面增强了碳纳米管的场致电子发射.该阴极制备工艺简单、发射特性优异,且容易实现大面积制备,可以应用到大面积场发射显示器件中.     

Field emission of GaN-filled carbon nanotubes: high and stable emission current

Field electron emission of GaN-filled carbon nanotubes, grown by microwave plasma enhanced chemical vapor deposition, was investigated. The detailed structural characterization shows that the filled nanotube has a GaN-core/C-shell structure, in which the GaN wire corresponds to a wurtzite structure. The field emission properties of the GaN-filled carbon nanotubes have been achieved with high and stable emission current. It is attributed to the unique cable-like structure, which makes the GaN-core/C-shell composite mechanically solid and chemically stable. This study suggests the GaN-filled carbon nanotube as an ideal candidate for future high-current and high-power field emitter applications.     

Negative ion emission accompanying the field electron emission from amorphous hydrogenated carbon

It was found that the field electron emission from the surface of amorphous hydrogenated carbon is accompanied by the emission of negative ions of hydrogen and hydrocarbons. This ion emission is explained by the formation and degradation of the local surface emission centers.     

Acoustic emission calibration instrumentation

An automatic calibration instrument was developed to improve the calibration accuracy of acoustic emission (AE) instrumentation. The instrument facilitates calibration by automatically displaying the maximum value of the stress used to produce AE calibration pulses and the AE pulse. A repeatable AE signal was generated by breaking a graphite rod on the test assembly. By measuring the breaking load of the rod and the maximum root-mean-square values of the resulting AE signals, a relative calibration of the AE measurement system was achieved. Low-noise amplifiers and filters were developed to improve the sensitivity of AE measurements by more than one order of magnitude over commercially available instruments; thus, the smaller signals obtained in parts testing can be detected     

Spontaneous emission in microcavities

The transverse distributions of intensity inside and outside an optical cavity produced by spontaneous emission from atoms inside the cavity are reviewed. The mode properties inside a closed passive one-dimensional cavity are summarised and the spatial distributions of emitted light for a passive cavity with partially transmitting mirrors are discussed. A qualitative theory describes the effects of an amplifying medium inside the cavity, covering the regimes both below and above the lasing threshold. Expressions are derived for the angular spread of the output light in the presence of gain. A theory based on rigorous general relations between gain and noise provides more complete results for the spontaneous emission noise from an amplifying slab within an optical cavity.