Superlattice semiconductor photocathode for the electron beam source with a high brightness and a long NEA-surface lifetime.

本研究的目的是用一种亮度高、表面寿命长的半导体光电阴极实现新型的电子源。研究发现，超晶格结构中的量子限制效应具有提取电子能散小的优点，而电子亲和势小、带隙能量大的半导体具有长NEA表面寿命的优点。研制了具有长NEA表面寿命的体相结构p-GaN光电阴极和用于产生小能散光电子的InGaN-GaN超晶格光电阴极。结果表明，p-GaN超晶格光电阴极的寿命是传统体相结构的GaN光电阴极的10倍以上，并且通过对InGaN-GaN超晶格光电阴极的量子产额谱观察到了有效的量子限制效应。

The aim of this study is the realization of the novel electron source using a semiconductor photocathode with high brightness and long NEA-surface-lifetime. This study found that the quantum confinement effect in a superlattice structure has the advantage of small energy spread of extracted electrons and the semiconductor which has small electron affinity and large band-gap energy had the advantage of long NEA-surface-lifetime. The p-GaN photocathode with a bulk structure for the long NEA-surface-lifetime and the InGaN-GaN superlattice photocathode for the generation of photoelectrons with small energy spread ware developed. As a successful result, the p-GaN photocathode achieved ten times longer lifetime than the GaAs photocathode with a bulk structure known as the conventional photocathode and the effective quantum confinement effect was observed by the quantum yield spectrum of the InGaN-GaN superlattice photocathode.