共查询到19条相似文献,搜索用时 125 毫秒
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本文采用考虑空间电荷影响的空间电场计算程序,对场致发射体进行模拟计算;初步研究了发射体的几何形状尺寸与其发射特性之间的联系。通过计算分析,可以认为发射体的尖端曲率半径及栅极的开口直径是影响发射体发射特性的最主要的因素。合肥国家同步辐射实验室的LIGA 深度光刻技术,能给出一个可行的几何结构。计算表明点阵密度为107/cm 2 的直径为6 m m 的硅发射体发射阵列,在80 V 的栅极电压下可以取得10 A 以上的发射电流 相似文献
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开关电源散热器的辐射发射 总被引:4,自引:0,他引:4
开关电源电路中,接地散热器提供了一条共模骚扰高频谐波电流的通路,使共模传导电磁干扰增加;非接地散热器切断了共模传导电磁干扰的通路,但增强了散热器辐射发射,射频辐射的增强能够引起设备误操作或者违反目前的电磁兼容性标准.文中分析功率开关管散热器产生辐射发射和共模传导电磁干扰的机理.采用有限元方法,通过电磁场数值计算,探讨非接地散热器的几何形状、尺寸和安装方式对其辐射发射的影响.数值计算结果表明:散热器面积越大、高次谐波频率越高,辐射电场幅值就越大,但是辐射电场幅值与散热器面积、高次谐波频率无线性关系;相同面积的散热器中,圆形散热器的散热效果最佳、辐射电场最小.因此,开关电源设计中,应根据散热效果、辐射EMI和共模传导EMI,综合考虑散热器面积、形状的选择,以及散热器是否接地. 相似文献
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本文利用广泛使用的PIC粒子模拟软件MAGIC模拟了楔型场致发射真空微电子三极管的一个单元的特性,该单元由一个楔型场致发射体,栅极和阳极组成。研究了栅极电压,阳极电压和发射体顶点半径等对发射电流的影响。给出了一个典型的楔型场致发射真空微电子三极管,当其阳极电压为500V,阳极与阴极相距4μm时的电子轨迹图。模拟结果表明场致发射的栅极开启电压为250V。并得到了三极管高频工作时动力学特性。 相似文献
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J.F. Mologni 《Microelectronics Journal》2006,37(2):152-157
A full three-dimensional model was implemented in order to investigate the electrical characteristics of conical and pyramidal isotropic etched emitters. The analysis was performed using the finite element method (FEM). The simulations of both emitters were modeled using a combination of tetrahedral and hexahedral elements that are capable of creating a mapped and regular mesh in the vacuum region and an irregular mesh near the surfaces of the emitter. The electric field strengths and electric potentials are computed and can be used to estimate the field enhancement factor as well as the current density using the Fowler-Nordheim (FN) theory. The FEM provides results at nodes located at discrete coordinates in space; therefore, the surface of the emitter can be generated through a function interpolating a set of scattered data points. The emission current is calculated through integration of the current density over the emitter tip surface. The influences of the device geometrical structure on its potential distribution, electric field and emission characteristics are discussed. 相似文献
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The authors present results on the analysis of two generic cone-shaped and wedge-shaped emitter-array diodes. The effects of the variations in device geometrical structure on the potential distribution, electric field, and emission current are discussed. The main geometric design parameters considered are the tip-to-collector distance, the emitter tip radius of curvature, and the intertip spacing. Pressure sensors based on these diode structures with one electrode fabricated on a pressure sensitive thin diaphragm were studied. The analysis shows that a cone-shaped emitter array has a larger emission current per emitter tip, but the wedge-shaped array has better pressure sensitivity 相似文献
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A nitrogen (N)-doped diamond-based electron emitter has been fabricated by the sintering technique prior to the chemical vapor deposition process in order to improve the uniformity. There are no spatial differences in reflective electron energy loss spectra (REELS) from the diamond-based electron emitter, suggesting that uniform surface conditions are obtained. The uniform electron emission from the obtained electron emitter is confirmed through emission current vs anode voltage characteristics measurements. It seems that the uniformity of the emitter surface results in uniform electron emission from the diamond electron emitter 相似文献
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Seong-Chan Bae 《Microelectronics Journal》2006,37(2):167-173
The field emission characteristics of an oxidized porous polysilicon were investigated with different annealing temperatures. Pt/Ti, Ir, and Au/NiCr were used as surface emitter electrodes, and Pt/Ti emitter showed highly efficient and stable electron emission characteristic compared with the conventional Au/NiCr electrode. Thin Ti layer played an important role in promotion of adhesion of Pt to SiO2 surface and uniform distribution of electric field on the OPPS surface. Additionally, the Ti layer efficiently blocked the diffusion of emitter metal, which resulted in more reliable emission characteristics. Pt/Ti emitter annealed at 350 °C/1 h showed the highest efficiency of 3.36% at Vps=16 V, which resulted from the improvement of interfacial contact characteristics of thin emitter metal to an oxidized porous polysilicon. Annealing above 400 °C showed that Pt/Ti and Ir emitter electrode were thermally more stable than Au/NiCr emitter. 相似文献
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《Electron Devices, IEEE Transactions on》1962,9(2):136-142
For the double-diffused transistor, a one-dimensional analysis is presented on the minority carrier injection properties of a diffused emitter junction. This junction is bounded on one side by a reverse biased collector and on the other by an ohmic contact of arbitrary recombination velocity. Furthermore, arbitrary magnitudes of minority carrier lifetime are assumed in both the emitter and base regions of this semiconductor device. Injection efficiency characteristics are graphically illustrated throughout a wide range of physical and geometrical parameters. Assuming, for example, variations in the emitter junction depth, injection properties are demonstrated for transistors exhibiting a fixed collector location and also for transistors exhibiting a fixed base width. A comparison is also shown between the calculated minority carrier injection from this analysis and from other, more approximate, methods. 相似文献
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Spontaneous emission characteristics from apertured microcavities are studied using quantum-dot light emitters. Spatial averaging over the emitter positions within the apertures significantly impacts the measured lifetime changes, but lifetime changes due to the aperture modes are still readily observed. A maximum increase of a factor of ~2.5 over the cavity-free emission rate is measured. We argue that, for a narrow bandwidth emitter, the microcavity enhancement can lead to nearly-single-mode and high-speed operation even in the spontaneous regime 相似文献
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场致电子发射具有高效、响应快等优点,有着广泛的应用前景。锥形和金字塔形尖端是两种常见的场发射尖端结构。主要分析了这两种尖端结构的场发射电学特性,并在此基础上提出了进一步实现结构优化的途径。为此,建立了两种尖端的三维模型,并利用有限元法深入讨论了结构尺寸,包括尖端曲率半径、尖端与阳极间距以及尖端高度对电场分布以及电场强度的影响。结果表明,减小尖端曲率半径、缩短尖端与阳极间距、以及选择适当的锥体高度是优化尖端场致电子发射性能的三个重要途径。在综合考虑电场分布以及电场强度的情况下,可以发现锥形尖端更有利于产生高密度小束径的低能电子束,而金字塔形尖端则更适用于高压力灵敏度的应用需求。 相似文献
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Demonstration of low voltage field emission 总被引:1,自引:0,他引:1
Adler E.A. Bardai Z. Forman R. Goebel D.M. Longo R.T. Sokolich M. 《Electron Devices, IEEE Transactions on》1991,38(10):2304-2308
The authors describe field emission from a thin-film field emitter array. The process used to fabricate the field emitters is based on the mold technique described by H.F. Gray and R.F. Greene (US patent 4,307,507). Each emitter chip consists of a 10×10 square array of field emitter tips and associated lead bonding pads. There is a 10-μm spacing between emitter tips. The bare chips were packaged by mounting to an alumina substrate, four to eight chips per substrate. The chips were tested in a demountable vacuum system equipped with a movable anode. The testing apparatus makes it possible to accurately measure currents as low as 100 nA at low duty. Fowler-Nordhein-like current-voltage characteristics were measured for most of the chips tested, indicating field emission. Substantial emission currents were observed at less than 20 V. The emitted current was collected almost entirely at the anode: the measured gate current was 1 to 5% of the emitted current 相似文献
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Turn-on voltage of about 30 V is observed in 1-μm gate-aperture Si field emitter arrays fabricated using oxidation sharpening and chemical mechanical polishing. Small emitter tip radius (~10 nm) was achieved from low temperature oxidation sharpening. The gate leakage current is observed to be less than 0.01% of emitter current over the range of measurement. Devices show excellent emission uniformity for different sized arrays. Current saturation was observed at high gate voltages because of low dopant concentration of the substrate. Below the saturation region, the current-voltage characteristics obey the Fowler-Nordheim field emission theory 相似文献