揭示外延生长的Na$_2$KSb光电阴极(111)表面电子结构
Revealing the (111) surface electronic structure of epitaxially grown Na$_2$KSb photocathode
AI总结：
通过化学气相沉积在石墨烯涂覆的SiC(0001)衬底上首次实现Na$_2$KSb薄膜的晶体外延生长，利用角分辨光电子能谱和密度泛函理论计算识别了Na$_2$KSb(111)表面不同终止的色散表面态，并证明Cs/Sb沉积激活后晶体有序性得以保持，为研究多碱Na$_2$KSb(Cs)光电阴极的电子结构和理性改进其性能开辟了途径。
摘要：
最近的一项研究确立了Na$_2$KSb(Cs)光电阴极作为自旋极化电子的高效发射体。然而，碱锑化物的电子结构仍然知之甚少。在这项工作中，我们报告了首次通过化学气相沉积（CVD）在石墨烯涂覆的SiC(0001)衬底上实现Na$_2$KSb薄膜的晶体外延生长。这些薄膜的高晶体质量使得能够使用角分辨光电子能谱（ARPES）直接研究材料的电子结构。通过将实验结果与密度泛函理论（DFT）计算进行比较，我们识别了源自Na$_2$KSb(111)表面不同终止的色散表面态。此外，我们证明了在通过沉积Cs和Sb激活后，薄膜的晶体有序性得以保持。这一发现为研究多碱Na$_2$KSb(Cs)光电阴极的电子结构以及理性改进其性能开辟了途径。
英文摘要：
A recent study has established the Na$_2$KSb(Cs) photocathode as a highly efficient emitter of spin-polarized electrons. However, the electronic structure of alkali antimonides remains poorly understood. In this work, we report the first crystalline epitaxial growth of Na$_2$KSb films, achieved via chemical vapor deposition (CVD) on a graphene-coated SiC(0001) substrate. The high crystalline quality of these films enabled a direct investigation of the material's electronic structure using angle-resolved photoemission spectroscopy (ARPES). By comparing the experimental results with density functional theory (DFT) calculations, we have identified dispersive surface states originating from different terminations of the Na$_2$KSb(111) surface. Furthermore, we demonstrate that the crystalline order of the film is preserved following its activation via the deposition of Cs and Sb. This finding opens a pathway for investigating the electronic structure of multialkali Na$_2$KSb(Cs) photocathodes and for rationally improving their properties.
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