超高真空系统中的残余气体对Ga_(0.75)Al_(0.25)N阴极表面光电性质影响的研究  

Research on the Influence of Foreign Gases on the Optoelectronic Properties of Ga_(0.75)Al_(0.25)N Photocathode Surface

作　　者：朱宇轩 杨明珠 何思译 ZHU Yuxuan;YANG Mingzhu;HE Siyi(School of Physics and Optoelectronic Engineering,Nanjing University of Information Science and Technology,Nanjing 210044,CHN)

机构地区：[1]南京信息工程大学物理与光电工程学院,南京210044

出　　处：《光电子技术》2021年第1期17-21,55,共6页Optoelectronic Technology

基　　金：国家自然科学基金青年基金项目(61705108);江苏省自然科学基金青年基金项目(BK20170959)。

摘　　要：根据四极质谱仪对超高真空激活系统中残余气体的检测结果,建立了残余气体在Ga_(0.75)Al_(0.25)N(0001)表面的吸附模型。利用密度泛函理论计算了残余气体分子在Ga_(0.75)Al_(0.25)N(0001)表面的吸附。结果表明,残余气体提高了表面功函数。功函数的变化是由吸附质与表面之间的偶极矩引起的,残余气体与阴极材料形成由体内指向表面的偶极矩,不利于光电子的逸出。在紫外波段,残余气体吸附表面的吸收系数小于Cs原子吸附表面的吸收系数。Based on the detection results of quadrupole mass spectrometer(QMS)on ultra high vacuum system,the adsorption systems of residual gases adsorbed on Ga_(0.75)Al_(0.25)N(0001)surface were built.Based on density function theory(DFT),the adsorption of residual gases on Ga_(0.75)Al_(0.25)N(0001)surface was calculated.Results show that residual gases enhance the surface work function.The changes of the work function were caused by the dipole moments between the adsorbates and the surface.The dipole moments caused by residual gases pointed to the surface from bulk,which was harmful for electron escaping from surface into vacuum.At the ultraviolet waveband,the absorption coefficients of surfaces with foreign gases were smaller than that of the Cs adsorbed surface.

关 键 词：Ga_(0.75)Al_(0.25)N(0001)表面 密度泛函理论 残余气体 功函数 吸收系数 

分 类 号：O462.3[理学—电子物理学]