离子束表面处理对光电阴极发射的影响  

Effect of ion-beam surface treatment on photocathode emission

作　　者：王国建 刘燕文 李芬 田宏 朱虹 李云 赵恒邦 王小霞 张志强 Wang Guo-Jian;Liu Yan-Wen;Li Fen;Tian Hong;Zhu Hong;Li Yun;Zhao Heng-Bang;Wang Xiao-Xia;Zhang Zhi-Qiang(Chinese Academy of Sciences Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院空天信息创新研究院,北京100190 [2]中国科学院大学,北京100049

出　　处：《物理学报》2021年第21期356-363,共8页Acta Physica Sinica

基　　金：国防预研究基金(批准号:31512010404-1);国家自然科学基金(批准号:61771454)资助的课题。

摘　　要：为研制大电流密度光电阴极,提出了一种制备锑铯光电阴极的新方法,采用专门的离子轰击技术使无氧铜表面纹理化,提高其吸附性能和光的吸收率,从而相对于未经处理的无氧铜可以大幅提高光电发射的性能.研究了表面处理前后的无氧铜基体锑铯光电阴极的发射特性.利用扫描电子显微镜分析了其表面结构,处理后的无氧铜为表面无颗粒、坚固、结构均匀的全金属结构体,使用此工艺无需修改无氧铜加工、焊接或其他光电阴极常规制造工艺.实验中,获得的无氧铜基体处理前后的光电阴极稳定发射的最大的光电发射电流密度分别为60.5和146.0 m A/cm^2,计算出相应的量子效率分别为2.67×10^(–3)和1.71×10^(–2),可知量子效率提高了5.41倍.分析认为,表面改性后的光电阴极的量子效率提高的主要原因来自于光吸收率的提高以及发射表面积增大.To meet the needs of high-frequency,miniaturized vacuum microwave devices,a new photocathode for microwave vacuum electronic device has been studied.Untreated oxygen-free copper,commonly used for photocathode substrate,exhibits relatively high photoemission characteristics.In this paper,we describe a specialized ion-beam bombardment procedure for textured copper surfaces,thereby improving the photoemission properties relative to untreated copper.The emission characteristics of antimony cesium photocathode on oxygen-free copper substrate before and after surface treatment are studied The photoemission and texture of post-treated oxygen-free copper surface are examined by scanning electron microscope.The results show that the treated surface has a particle-free,robust,uniformly highly-textured all-metal structure.This processing technology does not require to modify the copper machining and brazing,nor normal fabrication procedures of other photocathodes.In the experiment,the maximum photoemission current density of photocathode for the untreated substrate is 60.5 and that for the treated substrate is 146.0 mA/cm^(2),and their corresponding quantum efficiencies are calculated to be 2.67×10^(–3 )and 1.71×10^(–2),respectively.So,the quantum efficiency is enhanced by 6.41 times.The analysis indicates that the improvement of the quantum efficiency of the treated photocathode is mainly due to the enhancement of the light absorption rate.The results show that the photoemission is enhanced significantly after the substrate has been treated,and there is still much room for improvement.

关 键 词：光电阴极 离子束表面改性 激光驱动 量子效率 

分 类 号：O462.3[理学—电子物理学]