Abstract: The action of rare earth elements doped in Ag-BaO thin films is discussed, based on the colloidal particles theory and experimental results. It shows that, influenced by the size and shape of Ag nanoparticles, increasing optical absorption and improving transport condition are two ways to enhance the photoemissive current density. With the action of rare earth elements, the Ag particles become smaller and spheroid. As a result, the total surface square of Ag particles increases, the optical absorption increases, the equivalent barrier between a metallic particle and the host semiconductor decreases, and the transport condition improves. So, the rare earth elements can enhance the photoemission of Ag-BaO thin film.

Key words: photoemission, rare earth, thin films, nanoparticles

摘要： 根据光电阴极的固溶胶理论，结合实验结果对稀土元素在Ag-BaO薄膜中的作用及其对光电发射性能的影响进行了分析。结果表明，增强光吸收和改善光电子输运条件是提高Ag-BaO薄膜光电发射电流的两个因素，而Ag纳米粒子的粒度对这两个因素都有重要影响。由于金属纳米粒子的光吸收是表面等离子激元的吸收，稀土元素在Ag-BaO薄膜中对Ag纳米粒子的细化，球化和密集的作用，使纳米粒子总表面增大，有利于增强薄膜的光吸收能力。Ag纳米粒子的细化还能够增大等效洛仑兹振子能量，降低金属微粒与半导体等效界面位垒，改善光电子输运条件，因而稀土元素在Ag-BaO薄膜中可以起到提高Ag-BaO薄膜的光电发射性能的作用。

关键词: 光电发射, 稀土, 薄膜, 纳米粒子