Development of Field Emitters with Advanced Functions and Narrow Energy Spread

(a)功能先进的发射体：我们已经成功地利用干法和湿法蚀刻技术制造出了长宽比大于10的砷化镓场发射体。在GaAs发射极的电流-电压特性中观察到饱和行为，表明由Gunn效应产生的束状光束直接从GaAs发射极发射。我们利用多晶金刚石制备了新型的平面发射极。在15V的低栅极电压下，实现了低发射角的均匀发射。(b)窄能量扩散的发射体：我们使用并联型能量分析仪测量了单尖端Si场发射体发射电子的能量扩散。我们还利用圆柱形能量分析仪测量了单尖端Si场发射极发射电子的能量扩散，其不受发射角的影响。能量分布表明，一些被捕获的电子贡献了场发射。(C)新型场发射装置：我们已经成功地使用单尖端Si场发射装置在可见光至近红外光区观察到加速电压为20kv、光束电流为200nA的Smith-Purcell辐射。我们还开发了一种微型x射线管，该x射线管使用的是由石墨衬底蚀刻形成的新型石墨发射器。我们演示了时间分辨x射线照相，其时间分辨为10μsec。

(a)Emitters with advanced functions : We have successfully fabricated the GaAs field emitter with an aspect ratio larger than 10 using both dry-and wet-etching. The saturation behavior is observed in the current-voltage characteristics of the GaAs emitter, suggesting that the bunched beam generated by the Gunn effect is emitted directly from the GaAs emitter. We have fabricated the novel planar emitter using polycrystalline diamond. Uniform emission with low emission angle is observed at the low gate voltage of 15V.(b)Emitters with narrow energy spread : We have measured energy spread of the electrons emitted from the single-tip Si field emitter using a parallel-type energy analyzer. We have also measured energy spread f the electrons emitted from the single-tip Si field emitter using a cylindrical energy analyzer, which is not affected by the emission angle. The energy distribution indicates that some trapped electrons contribute the field emission.(C)Novels devices with field emitters : We have successfully observed Smith-Purcell radiation at an acceleration voltage of 20 kV and a beam current of 200nA in a visible-to-near infrared light region using a single tip Si field emitter. We have also developed a miniature size x-ray tube using the novel graphite emitter formed by the etching of a graphite substrate. We have demonstrated time-resolved x-ray radiography, whose time resolution is 10μsec.