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根据激活过程中光电流变化规律及原位光谱响应测试,模拟了GaAs光阴极表面势垒的形成过程,在光阴极表面双偶极子模型的基础上作了修正,建立了三偶极子模型。新模型认为,光阴极表面势垒由三个偶极层套构而成,第一偶极层由GaAs(Zn)--Cs+偶极子组成,第二偶极层由Cs2O偶极子组成,第三偶极层由GaAs-O-Cs偶极子组成,第二、三偶极层嵌入第一偶极层中。根据隧道效应与量子效率测试结果,确立了势垒中分段均匀的电势分布,计算得出势垒宽度为1.65 nm,有效电子亲和势为-0.44 eV。新模型的建立对理解光电阴极表面发射机理具有重要意义。
According to the photocurrent variation and in-situ spectral response test during the activation process, the formation process of GaAs photocathode surface barrier was simulated. Based on the double-dipole model of photocathode surface, the triple dipole model . According to the new model, the photocathode surface barrier consists of three dipole layers, the first dipole layer consists of GaAs (Zn) -Cs + dipoles, the second dipole layer consists of Cs2O dipoles, The third dipole layer is composed of GaAs-O-Cs dipoles, and the second and third dipole layers are embedded in the first dipole layer. According to the tunneling effect and the quantum efficiency test results, the uniform potential distribution in the barrier is established. The calculated barrier width is 1.65 nm and the effective electron affinity is -0.44 eV. The establishment of the new model is of great significance for understanding the surface emission mechanism of photocathode.