Understanding the Growth Dynamics Cs-Sb Thin Films via In-Situ Characterization Techniques: Towards Epitaxial Alkali Antimonide Photocathodes
Understanding the Growth Dynamics Cs-Sb Thin Films via In-Situ Characterization Techniques: Towards Epitaxial Alkali Antimonide Photocathodes
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通过原位表征技术了解 Cs-Sb 薄膜的生长动态：外延碱锑化物光电阴极
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
K. Shen
中科院分区：
文献类型：
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作者：
A. Galdi;J. Balajka;I. Bazarov;L. Cultrera;W. DeBenedetti;M. Hines;Cheng Hu;J. Maxson;L. Moreschini;H. Paik;C. Parzyck;K. Shen
碱金属锑化物光电阴极（如Cs3Sb）具有低发射度和高量子效率等优良性能，是下一代高亮度电子源的理想候选材料。文献中的大量研究集中在量子效率和寿命上，而较少报道化学和结构分析，尽管后者最终决定了光阴极的亮度。外延单晶薄膜将允许研究碱性锑化物光电阴极的固有特性，并优化它们以获得最大亮度，但这一目标仍然难以实现。一个强有力的限制因素是极端的空气敏感性，阻止了非原位结构和化学分析。利用扫描隧道显微镜对不同衬底上生长的Cs3Sb样品进行了形貌观察。在SiC衬底上生长的样品显示10倍大的岛屿比在其他衬底上生长的样品在相同的条件下。原位反射高能电子衍射的进一步研究表明，SiC上的生长动力学良好，使其成为Cs3Sb外延生长的优选衬底。
Alkali antimonide photocathodes, such as Cs3Sb, have attractive properties, such as low emittance and high quantum efficiency, which makes them excellent candidates for next-generation high-brightness electron sources. A large number of studies in literature focus on quantum efficiency and lifetime, and fewer report chemical and structural analysis, despite the latter ultimately determine the brightness at the photocathode. Epitaxial, single-crystalline films would allow to study the intrinsic properties of alkali antimonide photocathodes and to optimize them for maximum brightness, but this goal remains elusive. A strong limiting factor is the extreme air sensitivity, preventing ex-situ structural and chemical analysis. We used vacuum suitcase transfer to study the morphology of Cs3Sb samples grown on different substrates with scanning tunneling microscopy. Samples grown on SiC substrates show 10 times larger islands than samples grown on other substrates in the same conditions. Further studies with in situ reflection high energy electron diffraction demonstrate favorable growth dynamics on SiC, making it a preferable substrate for epitaxial growth of Cs3Sb.