Negative electron affinity photocathodes as high-performance electron sources. Part 1: achievement of ultrahigh brightness from an NEA photocathode
Negative electron affinity photocathodes as high-performance electron sources. Part 1: achievement of ultrahigh brightness from an NEA photocathode
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DOI：
10.1117/12.221575
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发表时间：
1995-09
期刊：
影响因子：
--
通讯作者：
A. Baum;W. Spicer;R. Pease;K. Costello;V. Aebi
中科院分区：
文献类型：
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作者：
A. Baum;W. Spicer;R. Pease;K. Costello;V. Aebi
亮度、能散和发射面积是电子显微镜和电子束光刻机等仪器电子源的关键参数。在开发作为这些应用的源的透射模式NEA光电阴极时，这些特性已在专用密封管中测量。测得1.5微米厚的光电阴极的平均横向能量为63 meV，0.5微米厚的光电阴极的平均横向能量为83 meV，已知光电阴极发射“热”电子。从1.7微米直径的发射区域获得841 A/cm 2的电流密度。这种高电流密度可以用表面俘获电子的横向漂移和扩散来解释。组合的角度和电流密度数据表明在3 kV下的亮度约为108 A/cm 2-sr。
Brightness, energy spread and emission area are key parameters of electron sources for instruments such as electron microscopes and electron beam lithography tools. In developing transmission-mode NEA photocathodes as sources for these applications, these characteristics have been measured in specialized sealed tubes. Average lateral energies were measured at 63 meV for 1.5 micron thick photocathode, and 83 meV for a 0.5 micron thick photocathode, which was known to be emitting `hot' electrons. A current density of 841 A/cm2 was obtained from a 1.7 micron diameter emission area. This high current density can be explained in terms of lateral drift and diffusion of surface trapped electrons. Combined angular and current density data indicate a brightness of approximately 108 A/cm2-sr at 3 kV.