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基于纳米晶Si的平面型阴极，并在其上覆盖一层氧化物薄膜。当栅压高于Au栅的功函数时，电子发射发生，发射效率随栅厚的减小而增加，对于5 nm Au栅的阴极，发射效率提高了4%.在Au薄膜中观察到大量的纳米孔，表明发射包括纳米孔下排列的纳米晶直接发射的电子。发射电子的能量分布对栅压有很强的依赖性，在2 ~ 4 eV的半高宽范围内，发射电子的能量分布变宽，并且随着栅压的增加，发射电子的能量谱向高能侧移动。此外，我们还测量了阴极的发射角。测量值估计约为4.5°，显示了平面阴极与传统场致发射体相比的优势。

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.