用变角XPS定量分析研究GaAs光电阴极激活工艺  

Quantitative Angle Dependent XPS Studies of Activation of GaAs Photocathode

作　　者：汪贵华[1] 杨伟毅[1] 宗志园[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》2002年第6期399-402,433,共5页Vacuum Science and Technology

摘　　要：用变角X射线光电子能谱 (XPS)技术分析了GaAs光电阴极的激活工艺 ,定量计算了阴极表面激活层和界面氧化层的厚度和组成。界面氧化物是由于O原子穿过激活层 ,扩散到GaAs与 (Cs,O)激活层的界面上而形成的。导入过量O会增加O GaAs界面层的厚度 ,而对 (Cs,O)激活层厚度影响较小。在激活过程中 ,严格控制和减少每次导入的O量是减少界面氧化层厚度 ,提高灵敏度的重要途径。在第一步激活后的阴极样品 ,通过较低温度的加热和再激活 ,能获得比第一步高出 30(Cs, 0) activated p-GaAs (100) surfaces were studied by quantitative angle dependent X-ray photoelectron spectroscopy (XPS). The thickness and composition of both the (Cs, 0) activation layer and the oxidation layer of the GaAs photocathode were quantitatively evaluated. The results show that oxygen in the activation layer may diffuse to the interfacial layer and oxidize it. Excess oxygen admission during activation strongly increases the thickness of the interfacial oxidation layer while the thickness of the (Cs, O) activation layer remains constant. It was shown that the interfacial oxidation layer can be minimized by careful control and reduction of oxygen admission at every (Cs, 0) activation step so as to improve the sensitivity of the photocathode. 30% higher sensitivity can be obtained by low temperature annealing and reactivating the initially activated samples because low temperature annealing decreases the interfacial oxidation layer thickness and considerably reduces the interfacial barrier height and width.

关 键 词：变角XPS 定量分析 GAAS 激活工艺 砷化镓 光电阴极 变角X射线光电子能谱 

分 类 号：TN15[电子电信—物理电子学] O462.3[理学—电子物理学]