光阴极材料GaAs/AlGaAs的组分分析  

Chemical Composition of Photocathode Materials GaAs/AlGaAs

作　　者：汪贵华[1] 杨伟毅[1] 常本康[1] 

机构地区：[1]南京理工大学电子工程与光电技术学院,南京210094

出　　处：《真空科学与技术》1999年第6期456-460,共5页Vacuum Science and Technology

摘　　要：为探索砷化镓光阴极的光电灵敏度的影响因素 ,利用X射线光电子能谱、二次离子质谱和电化学方法测试和分析了国内和国外GaAs光阴极材料GaAs/AlGaAs的C ,O含量和空穴浓度分布。实验发现 ,国内的材料在GaAs/AlGaAs界面及AlGaAs层的O含量分别为 7 6 %和 10 6 % ,C浓度分别为 5 2×10 18atoms/cm3和 1 0× 10 19atoms/cm3,而国外的材料的O含量相应为 1 0 %和 1 5%。国内的材料GaAs和AlGaAs层的空穴浓度分别为 7× 10 18～ 4× 10 19cm- 3和 8× 10 17cm- 3,而国外材料的相应值分别为 (1 8～ 2 0 )× 10 19cm- 3和 5× 10 18cm- 3。分析认为 ,层中及界面的C ,O杂质偏高和空穴浓度分布不尽合理使光电子扩散长度减小 ,后界面复合增大 ,导致了光电灵敏度下降。GaAs/AlGaAs layers,used as GaAs photocathode materials,were grown by metal organic chemical vapor deposition on GaAs substrates.Its chemical composition,and its hole concentration were studied with X ray photoelectron spectroscopy,secondary ion mass spectroscopy and conventional electrochemical analysis techniques.The results show that high carbon and oxygen impurity contents at GaAs/AlGaAs interface and in AlGaAs layers,and improper hole concentration are responsible for several effects,such as the shortening of minority carrier diffusion length,an increase of recombination rate at AlGaAs/GaAs interface,and lowering of photoelectron sensitivity of GaAs photocathodes.

关 键 词：光阴极 X射线 光电子能谱 二次离子质谱 砷化镓 

分 类 号：TN304.23[电子电信—物理电子学] TN204