Rb掺杂对K-Cs-Sb阴极材料光电性质的影响  

Effect of Rb Doping on Photoelectric Properties of K-Cs-Sb Cathode Material

作　　者：韩允锋 金睦淳[2] 任玲[2] 王兴超[2] 张锴珉 刘晓荣 钱芸生[1] 张益军[1] Han Yunfeng;Jin Muchun;Ren Ling;Wang Xingchao;Zhang Kaimin;Liu Xiaorong;Qian Yunsheng;Zhang Yijun(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China;North Night Vision Technology Co.,Ltd.,Nanjing 211106,Jiangsu,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]北方夜视技术股份有限公司,江苏南京211106

出　　处：《光学学报》2024年第4期219-226,共8页Acta Optica Sinica

基　　金：国家自然科学基金(62271259,U2141239);国家重大科学仪器设备开发专项(2016YFF0100400)。

摘　　要：通过掺杂Rb有助于改善碱锑化合物光电阴极的光谱响应并降低热发射。为了从理论上研究K-Cs-Sb光电阴极材料中掺Rb的作用机理,采用基于密度泛函理论的第一性原理方法,分别建立了K_(2)CsSb、K_(2)Cs_(0.75)Rb_(0.25)Sb、K_(2)Cs_(0.5)Rb_(0.5)Sb、K_(2)Cs_(0.25)Rb_(0.75)Sb、K_(2)RbSb 5种不同Cs/Rb比例(原子数分数之比)的K-Cs-Rb-Sb体模型以及相应的(111)表面模型,计算了其电子结构与光学性质。计算结果表明,对于不同Cs/Rb比例的K-Cs-Rb-Sb体模型,Rb掺杂对其光学性质的影响甚微。随着Rb/Cs比例的增加,体模型的形成能和形成焓以及表面模型的表面能变低,说明K-Cs-Rb-Sb化合物容易形成且稳定。此外,与传统的K_(2)CsSb相比,K_(2)Cs_(0.25)Rb_(0.75)Sb的功函数更大,电导率更大,同时又具有最小的禁带宽度和离化能,因此,Cs/Rb比例为1∶3的K-Cs-Rb-Sb阴极适合作为量子效率高、暗电流低且导电性好的光电发射材料。Objective Alkali antimonide photocathodes are widely used in many fields such as radiation detection,photon counting,and accelerator electron source due to their advantages of high quantum efficiency,long lifespan,short response time,and low preparation cost.Since K_(2)CsSb bi-alkali photocathode has high photosensitivity ranging from 300 nm to 650 nm,it is often used as the key component of large-area microchannel plate photomultiplier tube and dynode photomultiplier tube.KCs-Rb-Sb tri-alkali photocathodes may exhibit more outstanding performance in spectral response enhancement and thermionic emission suppression compared to conventional K_(2)CsSb bi-alkali photocathode.So far,there have been little theoretical researches on K-Cs-Rb-Sb tri-alkali photocathodes.Due to the difficulty in controlling the stoichiometric ratio of alkali metal elements during the actual preparation processes of K-Cs-Rb-Sb photocathodes,and in fact K-Cs-Rb-Sb trialkali photocathodes with different stoichiometric ratios have different photoemission properties,it is necessary to analyze the mechanism of Rb doping leading to different photocathode properties from the atomic and electronic perspective,thereby providing theoretical guidance for designing excellent alkali antimonide photocathodes.Methods The K_(2)Cs_(2-x)RbxSb bulk models and the(111)-oriented surface models with different Cs/Rb ratios corresponding to K_(2)CsSb,K_(2)Cs_(0.75)Rb_(0.25)Sb,K_(2)Cs_(0.5)Rb_(0.5)Sb,K_(2)Cs_(0.25)Rb_(0.75)Sb,and K_(2)RbSb were established.The K_(2)CsSb unit cell belongs to the DO3 cubic structure with a lattice constant of 0.8615 nm,and the space group is Fm-3m.According to the number of Cs atoms in K_(2)CsSb replaced by Rb atoms,the lattice constants of several K-Cs-Rb-Sb bulk models after atom replacements were obtained by Vegard law.On the basis of the K_(2)CsSb(111)Cs-terminated surface,six,eight,twelve,and sixteen Cs atoms were replaced from top to bottom,to obtain the K-Cs-Rb-Sb(111)surface models with different Cs/Rb ratios.To eliminate in

关 键 词：材料 K-Cs-Sb光电阴极 Rb掺杂 光电性质 第一性原理 

分 类 号：O462.3[理学—电子物理学]