Resolution improvement of low-voltage scanning electron microscope by bright and monochromatic electron gun using negative electron affinity photocathode
Resolution improvement of low-voltage scanning electron microscope by bright and monochromatic electron gun using negative electron affinity photocathode
复制标题
DOI：
10.1063/5.0005714
复制
发表时间：
2020-04
影响因子：
3.2
通讯作者：
Hideo Morishita;T. Ohshima;M. Kuwahara;Y. Ose;T. Agemura
中科院分区：
文献类型：
--
作者：
Hideo Morishita;T. Ohshima;M. Kuwahara;Y. Ose;T. Agemura
扫描电子显微镜（SEM）是分析各种样品表面的有力工具。在通常低于1 kV范围的低电压下进行SEM观察对于获得样品的表面信息是非常有效的。然而，在低电压范围内，分辨率受到电子源的亮度和能量扩散的限制。因此，为了提高分辨率，明亮的单色电子源是必不可少的。在本工作中，我们着重于一个电子枪与负电子亲和势光电阴极使用p型砷化镓和Cs-O吸附。与使用常规肖特基发射（SE）型发射体的SEM相比，在1 kV的加速电压下，原型SEM的分辨率提高了约16%。此外，结果表明，所测量的亮度与SE型发射器一样高（107 A/m2/sr/V），并且估计的能量扩展小于0.2eV，这比冷场发射型发射器窄。
The scanning electron microscope (SEM) is a powerful tool for analyzing the surface of various specimens. SEM observation at low voltage, which is typically lower than the 1 kV range, is very effective for obtaining surface information of specimens. However, at the low voltage range, resolution is restricted by the brightness and energy spread of electron sources. Therefore, to improve the resolution, a bright and monochromatic electron source is indispensable. In this work, we focused on an electron gun with a negative electron affinity photocathode using p-type GaAs and Cs–O adsorbates. The resolution of a prototype SEM was improved by approximately 16% compared with a SEM using a conventional Schottky emission (SE)-type emitter at the acceleration voltage of 1 kV. In addition, results showed that the measured brightness was as high as an SE-type emitter (∼107 A/m2/sr/V) and the estimated energy spread was less than 0.2 eV, which was narrower than that of a cold field emission-type emitter.