Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 15: Energy materials (other than photovoltaics)

HL 15.1: Vortrag

Dienstag, 2. April 2019, 09:30–09:45, H33

Ab-initio study of the electronic structure of Na2KSb and NaK2Sb for photocathode applications — •Raymond Amador and Caterina Cocchi — Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, Deutschland

In the search for novel materials for electron sources with enhanced quantum efficiency and minimised intrinsic emittance, multi-alkali antimonides are particularly promising in light of their relatively low band gap and electron affinity giving rise to emission in the near-infrared and visible region [1]. To fully exploit their potential, it is essential to reliably understand the electronic structure of these materials. First-principles methods such as density-functional theory (DFT) and many-body perturbation theory are suited for this purpose, as recently demonstrated in the case of CsK2Sb [2]. Here, we employ DFT to investigate the electronic structure of two Na-based alkali antimonides, namely Na2KSb and NaK2Sb. From the analysis of the band structure and the density of states, computed with exciting [3], we clarify the character of the electronic states in the gap region and rationalise their behaviour in comparison with previously investigated Cs-based compounds [2]. Our results represent the first step towards an in-depth characterisation of the photoemission processes in Na-based alkali antimonides.

[1] Musumeci et. al., Nucl. Instrum. Methods Physics 907, 209 (2018) [2] Cocchi, et. al. J. Phys.: Condens. Matter https://doi.org/10.1088/1361-648X/aaedee (2018) [3] Gulans et. al., J. Phys.: Condens. Matter 26, 363202 (2014)