InGaAs光电阴极制备工艺中的原位光电子能谱  

In-situ Photoelectron Spectroscopy of InGaAs Photocathode in Preparation Process

作　　者：李姗 张益军[1] 荣敏敏 李诗曼 石峰[1] 焦岗成 王自衡 钱芸生[1] Li Shan;Zhang Yijun;Rong Minmin;Li Shiman;Shi Feng;Jiao Gangcheng;Wang Ziheng;Qian Yunsheng(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing,Jiangsu 210094,China;Science and Technology on Low-Light-Level Night Vision Laboratory,Xi'an,Shaanxi 710065,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094 [2]微光夜视技术重点实验室,陕西西安710065

出　　处：《光学学报》2022年第1期199-206,共8页Acta Optica Sinica

基　　金：国家自然科学基金(61771245,61301023);微光夜视技术重点实验室基金(J20200102)。

摘　　要：为了探索InGaAs光电阴极高温净化工艺的最佳加热温度点,利用超高真空光电阴极制备与表征互联装置开展了不同加热温度点下的高温净化实验和表面铯/氧(Cs/O)激活实验。通过扫描聚焦X射线光电子能谱对化学清洗后、高温净化后以及表面激活后的InGaAs样品表面进行原位分析,检测不同温度点下表面杂质的脱附程度和化学元素组成变化。结果表明,样品表面的碳污染物和氧化物在625℃时都被完全去除,获得原子级清洁表面,但此时In元素会出现挥发现象,导致材料表面In含量降低,会使InGaAs材料的红外响应特性不明显,因此600℃被认为是最佳加热温度。结合原位紫外光电子能谱发现二次电子截止边随着温度的升高不断向高结合能的位置偏移,这表明高温净化能有效降低表面功函数值,而Cs/O激活能进一步降低表面功函数值,获得负电子亲和势,提高InGaAs光电阴极的近红外光电发射性能。In order to explore the optimal heating temperature of the InGaAs photocathode, the high-temperature cleaning experiments were carried out at different temperatures by using the ultra-high vacuum interconnection setup for photocathode preparation and characterization, and Cs/O activation experiments were followed. By scanning focused X-ray photoelectron spectroscopy, in-situ analysis of InGaAs samples after chemical cleaning, heat cleaning, and surface activation was performed, to detect the desorption of surface impurities and the change of chemical element composition at different temperatures. The results show that the carbon contaminants and oxides are completely removed at 625 ℃, resulting in an atomically clean surface. However, the In element is volatilized at this time, which leads to the decrease of In composition and makes the infrared response of InGaAs material unobvious. Therefore, 600 ℃ is treated as the optimal heating temperature. Combined with in-situ ultraviolet photoelectron spectroscopy, it is found that the secondary electron cut-off edge continuously shifts towards higher binding energy as the temperature rises, indicating that high temperature cleaning can effectively reduce the work function. After Cs/O activation, the work function value is further reduced, and the negative electron affinity state is achieved, which improves the near infrared photoemission performance of the InGaAs photocathode.

关 键 词：材料 InGaAs光电阴极 光电子能谱 高温净化 铯/氧激活 

分 类 号：TN233[电子电信—物理电子学]