共查询到20条相似文献,搜索用时 187 毫秒
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高温超导体处在临界温度以下时,能隙会引起体内电子分布的改变。本文在考虑到能隙对体内电子分布影响时,分析了高温超导体的场致发射电流密度和场致发射电子能谱。 相似文献
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采用质点网格法(particle-in-cell),利用MAGIC软件模拟了场致发射的物理过程.对两 种典型的场致发射模型(Spindt阴极发射体和金刚石薄膜发射体)分别进行了模拟.对Spind t阴极发射,研究了发射特性与尖端尺寸,尖端与栅极面的相对高度的关系.对金刚石薄膜发 射,比较了三极管和四极管的发射特性,以及薄膜面积对发射特性的影响,得出金刚石薄膜 发射体优于Spindt发射体的特性.
关键词:
场致发射
MAGIC程序
Spindt发射体
金刚石薄膜发射体 相似文献
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生长温度对纳米氧化锌场发射性能的影响 总被引:1,自引:1,他引:0
采用锌粉和银粉为蒸发源,用热蒸发法不同温度下制备了四针状纳米氧化锌,并以单独的锌粉做对照。采用扫描电子显微镜(SEM)观察其形貌,X射线衍射(XRD)谱表征其晶体结构。采用丝网印刷方法将其制备为场致电子发射阴极,将阴极与印刷有荧光粉的阳极板组装成二极结构场致发射显示屏,并进行了场致电子发射特性对比实验。结果表明较高温度制备的氧化锌具有较好的场致发射性能;掺杂银粉的蒸发源制备的样品的发射性能明显优于没有掺杂银粉的样品。实验证明ZnO是一种优良的场致发射冷阴极材料,在真空电子方面具有广阔的应用前景。 相似文献
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在超高真空系统中对基于丝网印刷方法制备的碳纳米管薄膜的场蒸发效应进行实验研究. 实验发现, 碳纳米管薄膜样品存在场蒸发现象, 蒸发阈值场在10.0-12.6 V/nm之间, 蒸发离子流可以达到百皮安量级; 扫描电子显微镜分析和场致电子发射测量结果表明, 场蒸发会使碳纳米管分布变得更加不均匀, 会导致薄膜的场致电子发射开启电压上升(240→300V)、场增强因子下降(8300→4200)、蒸发阈值场上升(10→12.6V/nm), 同时使得薄膜场致电子发射的可重复性明显变好. 场蒸发也是薄膜自身电场一致性修复的表现, 这种修复并非表现在形貌上, 而是不同区域场增强因子之间的差距会越来越小, 这样薄膜场致电子发射的可重复性和稳定性自然会得到改善. 相似文献
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本文按Schottky方程给出热场发射微波枪阴极电流之值来确定PARMELA程序在每一时间步长内输入粒子数,使PARMELA程序能用来作热场发射微波枪电子的动力学计算,改善了把PARMELA程序不加修改直接用于热场发射微波枪计算而带来的不合理图象。 相似文献
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We theoretically investigated different thermal relaxation participating in the ultrafast thermionic emission processes on gold film surface with a femtosecond pulse excitation. The thermionic emission regimes under the two temperature relaxation and the thermal diffusion relaxation were demonstrated. The simulations showed that the thermionic emission properties can be defined in the regime under two temperature relaxation by reducing the laser fluence, or widening the pulse duration or increasing the laser wavelength. It was also found that there exists a transition between the two distinct thermionic emission regimes under peculiar laser parameters of laser fluence, pulse duration and laser wavelength. The results were explained as significant intervene of laser irradiation parameters into gold film thermal relaxation processes. 相似文献
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采用区域熔炼法成功制备出了高质量,高纯度,大尺寸的LaB6单晶体. 系统分析了制备过程中每个参数对LaB6单晶生长的影响,确定了晶体生长最佳工艺为:样品转速为30 r/min,生长速度为8-10 mm/h. 分析了单晶LaB6 (100) 晶面的热电子发射性能,结果表明,当阴极温度为1873 K时,最大热发射电流密度为44.36 A/cm2;利用 Richardson 直线法求出了绝对零度逸出功和有效逸出功分别为1.99和2.59 eV. 场发射测试结果表明,单晶LaB6场发射单尖最大场发射电流密度达到4.9×106 A/cm2,场发射因子为41500 cm-1,表现出良好的场发射性能. 因此单晶LaB6作为热阴极和冷阴极都具有很广阔的应用前景.
关键词:
区域熔炼法
6')" href="#">单晶LaB6
热发射性能
场发射性能 相似文献
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A. B. Petrin 《Journal of Experimental and Theoretical Physics》2009,109(2):314-321
We suggest a general approach to considering the thermionic, field, and thermionic field emissions of electrons from metals. For this purpose, based on the standard model of free electrons in a metal, we suggest a numerical method for determining the transmission coefficient through the potential barrier at the metal-vacuum interface suitable for an arbitrary barrier. This method is free both from the approximations based on the saddle-point approximation and characteristic of the analytical models for thermionic emission and from the approximations for the tunneling coefficient through the potential barrier characteristic of the models for field emission. Based on numerical simulations, we determine the thermal effect of the emission and ascertain that a very sharp transition from surface cooling by electron emission to heating occurs at certain electric field and temperature. We explain the triggering mechanism of the explosive electron emission observed during micropoint explosions by this phenomenon. The explosive emission is shown to begin when the level of the potential barrier at the micropoint tip drops below the Fermi level in the metal. 相似文献
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对Ti/6H-SiC Schottky结的反向特性进行了测试和理论分析,提出了一种综合的包括SiC Schottky结主要反向漏电流产生机理的反向隧穿电流模型,该模型考虑了Schottky势垒不均匀性、Ti/SiC界面层电压降和镜像力对SiC Schottky结反向特性的影响,模拟结果和测量值的相符说明了以上所考虑因素是引起SiC Schottky结反向漏电流高于常规计算值的主要原因.分析结果表明在一般工作条件下SiC Schottky结的反向特性主要是由场发射和热电子场发射电流决定的. 相似文献
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为了研究二极管爆炸电子发射初始阶段阴极表面复杂的物理现象及规律, 建立了由场致电子发射阴极构成的一维平板真空二极管物理模型,通过自行编程数值求解泊松方程, 考虑了发射出的电子对阴极表面电场的非线性影响,自洽模拟得到了阴极表面电场随时间的变化情况. 模拟结果表明,爆炸电子发射初期,阴极表面电场随时间的增加而呈现出不断振荡的规律, 且振荡幅度越来越小,最终到达一个稳态的值,二极管两极板之间的外加电场越大, 阴极表面稳态电场的绝对值越大;电场增强系数越大,阴极表面稳态电场的绝对值越大. 在整个时间演变过程中,阴极表面的实际电场强度决定着阴极发射的电流密度大小, 反过来阴极发射的电流密度又会影响到阴极表面的电场. 相似文献
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Guangqing Du Qing Yang Feng Chen Xiangwei Meng Hao Bian Jinhai Si Xun Hou 《Applied Physics A: Materials Science & Processing》2013,112(2):479-483
A high-fidelity numerical model for investigations of the ultrafast heating is highly desirable for simulating the pulsed laser damage and the ultrafast electron emission characteristics. However, realization of accurate predictions of thermal dynamics and thermionic electron emission remains challenging due to the high non-equilibrium state, in which the equilibrium heating parameters are invalid. Here, we report an axisymmetric two-dimensional (2-D) high-fidelity numerical model for predictions of the thermionic emission with respect to the temperature-dependent dynamics parameters. The spatio-temporal temperature evolution dynamics and the thermionic emission rate characteristics on Au film target are demonstrated, whose credibility is approved by the Au film ablation threshold experiments. 相似文献
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The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied.Under different initial conditions,we discuss the effects of quantum interference and detuning of external driving field on atomic spontaneous emission properties.For the larger detuning,the interesting phenomena of the spectral line narrowing are found which stem from the contribution of external driving field. 相似文献
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采用简单物理气相沉积法制备出取向和非取向的氧化锌纳米棒,他们的场致电子发射性能测量结果表明,ZnO纳米棒具有较好的场发射性能,但是高度取向的ZnO纳米棒阵列并不利于获得高的场致电子发射电流密度.这可能是由于高密度ZnO纳米棒之间具有较高的屏蔽效应,降低了ZnO纳米棒阵列的场放大因子,从而影响了其场发射性能.相反,非取向ZnO纳米棒由于相互之间的屏蔽效应比较弱,而且表面存在容易成为发射中心的微小突起,表现出较好的场发射效果.这些结果不仅有助于加深我们对准一维纳米材料场致电子发射性能的理解,也为未来场发射电子器件的实际应用提供了可靠的依据.
关键词:
氧化锌
场发射
非取向 相似文献
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Parham Yaghoobi 《Solid State Communications》2011,151(17):1105-1108
Light-induced heating of a typical bulk conductor to thermionic electron emission temperatures usually requires high-power lasers. This is because of the efficient dissipation of heat generated at the illuminated spot to the surroundings, since electrical conductors are normally also good thermal conductors. We show that the situation can be drastically different in a carbon nanotube forest and a spot on the surface of the forest can be heated to above 2000 K using a low-power beam of visible light, leading to localized thermionic electron emission. This unique phenomenon may be explained by a rapid drop in thermal conductivity with increase in temperature, leading to a positive feedback that thermally isolates an island on the forest. Applications include thermoelectrics, photocathodes, optical switches, solar cells and even solar displays. 相似文献