Fabrication and ultraviolet photoemission characteristics of novel Au photocathodes
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摘要: 采用直流磁控溅射法制备了不同厚度的金纳米薄膜，在高纯氮气气氛、800 ℃条件下快速退火，在石英基底上制备了具有表面微纳颗粒的新型金阴极。应用扫描电子显微镜对阴极的表面形貌进行表征，结果表明：阴极表面形成了均匀分布的金纳米颗粒，平均粒径随金纳米薄膜厚度的增加（5 nm至20 nm）从300 nm增大到800 nm。在190~360 nm紫外光下，对阴极的光电子发射特性进行了研究，结果表明：相对于平面阴极，新型金阴极的光电子发射效率提高了10倍以上，最高可达到平面阴极的16倍，且随颗粒粒径的减小而增大。采用三步光电发射模型对上述结果进行理论分析，表明阴极光电效率的提高主要由于阴极光电发射面积的增加和局域强电场导致的表面势垒降低。Abstract: The DC magnetron sputtering was explored to fabricate Au thin films with thicknesses of 5, 10, 15, 20 nm on the silica substrates. These films were annealed in high purity nitrogen ambient at 800℃ and Au particles of different diameters were obtained on the silica substrates. The novel Au photocathodes were prepared by depositing a layer of 50 nm Au film on the silica substrates with Au particles. SEM showed that Au photocathodes with particles ranging from 300-800 nm were obtained. The photoemission characteristics of Au photocathodes under ultraviolet light between 190-360 nm were obtained, which indicated that the novel Au photocathodes with nano-particles emitted 10 times more photoelectrons than the plane Au photocathodes. This result is explained by semi-classical three-step model of photoemission.
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Key words:
- photocathode /
- Au nano-films /
- surface structure /
- UV photoemission characteristics /
- surface potential
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