Study on enhancement in emission current of plane-type cathodes based on nanocrystalline silicon

采用脉冲激光烧蚀技术制备了纳米晶硅表面覆盖氧化膜的平面型阴极。电子发射发生在栅极电压高于Au栅极功函数处，并且发射效率随栅极厚度的减小而增加，对于5nm Au栅极的阴极，发射效率提高了4%。在Au薄膜上观察到大量的纳米孔，表明发射包括电子直接从纳米孔下排列的纳米晶体发射。发射电子的能量分布与栅极电压有较强的依赖性，在FWHM中，栅极电压在2 ~ 4 eV范围内分布较宽，且随着外加电压的增加，发射电子能谱向高能侧移动。此外，我们还测量了阴极的发射角。测量值估计约为4.5°，显示了与传统场发射极相比，平面阴极的优势。

Planar-type cathodes based on nanocrystalline Si covered with a thin oxide film fabricated using a pulsed laser ablation technique were demonstrated. The electron emission occurred at the gate voltage higher than the work function of the Au gate, and the emission efficiency increased with decreasing gate thickness and was improved up to 4 % for the cathode with 5nm Au gate. A lot of nanoholes in the thin Au film were observed, suggesting emission included electrons directly emitted from nanocrystalline aligned under nanoholes. The energy distribution of emitted electrons shows strong dependence on the gate voltage that the distributions become broader from 2 to 4 eV in FWHM, and the spectrum moves to the higher energy side with the increase in the applied voltage. In addition, we measured the emission angle of the cathode. The measured value was estimated about 4.5°, showing an advantage of a planer cathode in comparison with a conventional field emitter.