共查询到20条相似文献,搜索用时 31 毫秒
1.
Kang W.P. Wisitsora-at A. Davidson J.L. Kerns D.V. 《Electron Device Letters, IEEE》1998,19(10):379-381
A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp2 content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters 相似文献
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Bryan P. Ribaya Darrell L. Niemann Joseph Makarewicz Norman G. Gunther Cattien V. Nguyen Mahmud Rahman 《Solid-state electronics》2008,52(10):1680-1686
In this paper we present an empirical study of some dynamic properties of an individual carbon nanotube (CNT) field emission electron source system. We propose a circuit model that represents the CNT cathode to anode diode as a capacitor in parallel with a voltage-controlled variable resistor. The transient response of the CNT electron source system to the falling edge of a voltage step input was evaluated. For input voltages below the threshold voltage for field emission, the nanotube loop is effectively open and the circuit response is consistent with a discharging capacitor. On the other hand, for input voltages above field emission threshold, the nanotube loop conducts and now the capacitor discharges to a certain extent through the nanotube loop as well. Field emission current versus voltage data also shows that the resistance across the CNT cathode to anode diode varies as a function of applied voltage. Below turn-on voltage, the diode behaves as an open circuit (4 TΩ at the ammeter noise floor). Above turn-on voltage, resistance falls exponentially, as expected from the Fowler–Nordheim equation for cold field emission current. Experimental current–voltage data is presented for a simple emitter array consisting of two CNTs with equal lengths. Despite the similarity in their lengths the turn-on voltages of the nanotubes varied significantly, viz. 26 V versus 109 V. This large difference in the turn-on voltages can be attributed to tip imperfections. For advanced array applications such as high-throughput parallel e-beam lithography, in which precise dose control is necessary, the diode circuit model will be useful for controlling individually addressed nanotubes to account for dissimilar field emission properties. The model may also be applied to optimize the design of a SEM incorporating a single CNT electron source. 相似文献
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《Electron Devices, IEEE Transactions on》1964,11(3):81-89
The present work treats the transport of noise, originating at a thermionic cathode, across a planar crossed-field diode. A multivelocity Monte Carlo analysis is used to simulate thermionic emission by using random numbers to generate electron emission times and velocities. Trajectories for many charges are followed through the diode space by means of a high-speed digital computer. Measurements performed on a planar triode model for the crossed-field diode show that the anode noise current increases rapidly near the critical magnetic field, at which the stream just grazes the anode. The theory agrees well with these experimental findings. The Monte Carlo study predicts the increase of both the normal anode velocity fluctuations and the spread of the velocity distribution with magnetic field. This is caused mainly by the "geometrical" spreading of the initial velocity distribution. The crossed-field potential minimum exhibits no instabilities in the planar model. The noise current smoothing at low frequencies in ordinary streams is predicted for moderate fields but disappears near the critical field. 相似文献
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《Electron Devices, IEEE Transactions on》2006,53(11):2674-2680
This paper presents results of computational and experimental studies of carbon nanotube (CNT) cathodes in gridded focusing guns intended for traveling-wave tube applications. With a curved CNT cathode, a cold beam emission of 11 mA was observed in a diode configuration. Two gridded focusing cathodes pasted with CNTs were then fabricated. When the applied cathode voltage was -0.86 kV, both grid and anode were at ground potential, and the cathode-to-grid distance was 200 mum, the dc emission current from the first gridded CNT cathode was measured to be 4.2 mA. The triode field emission characteristics with two accelerating stages in pulse operation were also examined. With the cathode voltage at -4 kV, a cathode-grid potential difference of 1.38 kV, and a pulsewidth of 20 mus, the measured pulsed current emission was 4.6 mA. The measured current was found to agree with MAGIC2D simulation results. Furthermore, by configuring a double-gridded focusing gun, a significant improvement in the beam focusing data collected through computer modeling was seen 相似文献
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在一定的假定条件下,考虑空间电荷影响,平面平行真空微电子(P—VMD)二极管中电流一电压近似按二分之三次方关系式工作。本文在此关系式及Forler—Nordheim场发射方程的基础上,通过解简化立方方程,进一步推导出管内的电位、电场强度、电子速度和空间电荷密度的分布函数。P-VMD二极管在保持管内结构与阴极表面电场强度不变,并工作在典型工作状态(归一化电位系数P=2/3)情况下,考虑空间电荷影响时的阳极电压、阳极电场强度和阳极电子速度分别比无空间电荷影响时增加约50.00%,73.21%和22.47%。P—VMD二极管内的空间电荷密度分布函数为正割函数,在阳极表面附近为最小,在阴极表面处为无穷大,这是由于本文假设在阴极表面处的电子初速度为零的缘故。 相似文献
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Currently a lot of electron emission experiments both in carbon nanotubes with top curvature radius <1 nm, and in emitters as short as 103 nm with top curvature radius of some tens nanometer are carried out. Experimental results can be explained by a tunnel emission through potential barrier in vacuum near the solid-state cathode border making use of Fowler-Nordheim law. However, in case of cathodes with radius of top curvature less than 100 nm this law is not valid.To proof this statement, the potential of an autoemission diode consisting of a tip cathode located on a flat metal base and flat anode, its dependence on the shape, height of the tip as well as voltage drop on it were calculated in this paper. It has been shown that with cathode tip height and its radius of curvature decreasing (?100 nm) the transparency of the potential barrier depends non-linearly on the anode voltage in the Fowler-Nordheim coordinates when the cathode tip height decreases from 1000 down to 150 nm. To obtain a measurable autoemission current, work function must not exceed the uniform field’s potential drop between cathode top and its base. Deduced is the analytic formula for the electric field potential that extends approximation features for real cathodes shapes and enables more accurate electric field modeling at the surface. 相似文献
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The degradation rate of the emission current of the Spindt-type field emitter arrays in the display environment has been measured. The relative degradation rate is found to be a function of the square of emission current and proportional to the anode bias (voltage). A life model is presented that leads to development of an analytical rate equation of emission current degradation. Based on this model, there is a steady-state level at which the emission current is stable. The steady-state emission current depends on anode bias, background pressure in the package and cleanliness of anode and cathode surfaces. Experimental results are consistent with the rate equation derived from the model. Since the model does not include any material and process that make the cathode, it could probably apply to any field emission cathodes. 相似文献
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Chun Gyoo Lee Sang Jo Lee Sung Hee Cho Eung Joon Chi Byung Gon Lee Sang Ho Jeon Sang Hyuck Ahn Su Bong Hong Deok Hyeon Choe 《Electron Device Letters, IEEE》2004,25(9):605-607
By approaching the counter electrode to the carbon nanotubes (CNT) emitter, remarkable reduction of the cathode operating voltage has been accomplished in the under-gate CNT cathode structure. The peak emission current density of 2.5 mA/cm/sup 2/, which is sufficient for high brightness CNT field emission display, was obtained at the cathode-to-gate voltage of 57 V when the CNT-to-counter electrode gap was 2.2 /spl mu/m. The gate current was less than 10% of the anode current. The CNT cathode with low driving voltage can help the cost-effective field emission display implemented. 相似文献
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通过发展新的活性物质成分系统及其制备方法以提升钪系阴极的电子发射性能,是当今热阴极特别是大电流密度阴极领域的研究重点。该文提出一种由多元金属氧化物构成的新型高活性浸渍物质,显著提升了钪在阴极中的添加比例,大幅提高了阴极的发射电流密度。将冷冻干燥法应用到该活性物质前驱体的制备过程中,有效解决了传统固相合成方法在机械式破碎、研磨和混合等工序中存在的不可控、不均匀等问题。采用了新的成分系统与新的制备方法制得活性物质的阴极,在真空二极管测试和电子枪测试中分别取得了超过500 A/cm2和218.5 A/cm2的脉冲发射电流密度。在二极管直流测试条件下,阴极的寿命测试进行了10500 h后仍未出现发射电流下降的现象;而在电子枪中的大工作比(5%)脉冲测试条件下,阴极在工作了2010 h后仍维持了超过50 A/cm2的较大发射电流密度。借助深紫外—光/热发射电子显微镜(DUV-PEEM/TEEM)分析发现,相较传统的钪系阴极,新制备的大电流密度阴极表面的热电子发射位点数量增加,微区发射面积显著增大。最后,提出一种“二叉树”发射模型,以期阐释钪系阴极采用新活性物质后获得高发射特性的物理机制。 相似文献
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Measurements of the near-field intensity distributions of three lead-sulfide-selenide diode lasers operating near 4.8 μm have been made as a function of injection current. Localized emission in the near field exhibits peaked structure of full width from 5 to 10 μm for operation above threshold. From the dependence of the emission profiles on injection current estimates of 25 cm-1and 0.09 cm/A are made for the distributed loss and gain coefficients for one of the lasers. Optical confinement perpendicular to the p-n junction can be explained in terms of the homojunction properties. 相似文献
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在传统AlGaN/GaN肖特基二极管中,阳极漏电始终是制约器件耐压提高的一个重要因素。因此文中研究了在缓冲层中生长P型埋层并与阳极相连的AlGaN/GaN肖特基二极管结构 AC-PBL FPs SBD来抑制阳极的泄漏电流。同时,在二极管的两级均加上场板来调制该器件的表面电场分布。经过仿真验证可知,该结构的阳极关断泄漏电流得到了有效抑制,同时辅助耗尽沟道内的2DEG,扩大空间电荷区,进而提高了器件的耐压特性。该结构的击穿电压为733 V,与传统GET SBD器件相比,击穿电压提高了近3.4倍,Baliga优值提升了近11.6倍,说明该器件可以应用在电力电子线路中。 相似文献
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Jung-Hyeon Park Hyung-Il Lee Heung-Sik Tae Jeung-Soo Huh Jung-Hee Lee 《Electron Devices, IEEE Transactions on》1997,44(6):1018-1021
Lateral field emission diodes were fabricated by using separation by implantation of oxygen (SIMOX) wafer and their current-voltage characteristics (I-V) were analyzed. Applying conventional photolithography and local oxidation of silicon (LOGOS) process, we fabricated single-crystalline lateral silicon field emitters with very sharp cathode and anode tips and very short cathode to anode spacing ranging from 0.3 to 0.8 μm as well. Two different types of tips, tapered and wedge-shaped emitters, were typically formed according to oxidation time. The turn-on voltages for both types of diodes were as low as 22~25 V and the emission currents were as high as 6 μA/tip at voltages of 35~38 V. From the Fowler-Nordheim (FN) equation, field emitting area (A) and field enhancement factor (β) for both types of diodes were estimated to explain the low turn-on voltages and the high emission currents 相似文献
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FED显示驱动电路结构及其场发射特性分析 总被引:2,自引:0,他引:2
从场发射的基本原理出发,分析了影响场发射电流的内外因素。阴极表面强电场是产
生发射电流的必要条件,但像素的不均匀性和场发射特性的非线性导致无法产生精确的发射电流,由此带来了亮度调节的可控性差;阴极驱动电路作为发射电流回路的一部分,其电路结构直接影响发射电流的控制特性,分析表明电流驱动模式能对阳极束电流进行精确控制,是实现FED亮度控制的理想驱动方式。 相似文献
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S. Schols S. Verlaak C. Rolin D. Cheyns J. Genoe P. Heremans 《Advanced functional materials》2008,18(1):136-144
The cover shows an organic light‐emitting diode with remote metallic cathode, reported by Sarah Schols and co‐workers on p. 136. The metallic cathode is displaced from the light‐emission zone by one to several micrometers. The injected electrons accumulate at an organic heterojunction and are transported to the light‐emission zone by field‐effect. The achieved charge‐carrier mobility and in combination with reduced optical absorption losses because of the remoteness of the cathode may lead to applications as waveguide OLEDs and possibly a laser structure. (The result was obtained in the EU‐funded project “OLAS” IST‐ FP6‐015034.) We describe an organic light‐emitting diode (OLED) using field‐effect to transport electrons. The device is a hybrid between a diode and a field‐effect transistor. Compared to conventional OLEDs, the metallic cathode is displaced by one to several micrometers from the light‐emitting zone. This micrometer‐sized distance can be bridged by electrons with enhanced field‐effect mobility. The device is fabricated using poly(triarylamine) (PTAA) as the hole‐transport material, tris(8‐hydroxyquinoline) aluminum (Alq3) doped with 4‐(dicyanomethylene)‐2‐methyl‐6‐(julolindin‐4‐yl‐vinyl)‐4H‐pyran (DCM2) as the active light‐emitting layer, and N,N′‐ditridecylperylene‐3,4,9,10‐tetracarboxylic diimide (PTCDI‐C13H27), as the electron‐transport material. The obtained external quantum efficiencies are as high as for conventional OLEDs comprising the same materials. The quantum efficiencies of the new devices are remarkably independent of the current, up to current densities of more than 10 A cm–2. In addition, the absence of a metallic cathode covering the light‐emission zone permits top‐emission and could reduce optical absorption losses in waveguide structures. These properties may be useful in the future for the fabrication of solid‐state high‐brightness organic light sources. 相似文献
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The emission efficiency of novel surface conduction electron-emitters corresponding to tilted angles (thetas) of a nanogap-typed driving cathode is optimised. Among the parameters of the emitter profile, the apex angle is the most significant because the smaller angles induce a higher electric field. The higher electric field then attracts more particles into vacuum and then increases the emission current. However, the structure of the driving cathode limits the electron trajectory while the angle decreases, and it reflects that the portion of collected current by the anode decreases and results in a drop in emission efficiency. The electric field with larger tilted angles will be weakened, but most of the emitted electrons could be collected by the anode, which increases emission efficiency. This shows there is highest emission efficiency (about 37%) under an optimum angle (thetas) of 60deg owing to a trade-off between emission efficiency and emitter apex. 相似文献
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为发展场致发射冷阴极毫米波电真空辐射源器件, 对利用大面积碳纳米管冷阴极产生大电流、高电流密度电子注的电子光学系统进行了研究.通过在Pierce电子枪阴极表面引入栅网结构, 解决了碳纳米管冷阴极场致发射所需的强电场和电子聚束问题.在碳纳米管冷阴极实验测试数据的基础上, 采用粒子模拟软件对上述电子光学系统进行了仿真.研究了栅网对注电流、注腰半径和电子注散射的影响, 分析了阳极电压和外加轴向磁场对电子注的聚束作用.优化后的仿真结果表明在阴极发射面为3.03 cm2时, 该电子光学系统能够产生210 mA、60 kV, 电流密度为6.7 A/cm2, 最大注半径为1mm的电子注. 相似文献