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Single and multi domain buckled germanene phases on Al(111) surfaceстатья
Статья опубликована в высокорейтинговом журнале
Статья опубликована в журнале из списка Web of Science и/или Scopus- Авторы: Muzychenko Dmitriy A., Oreshkin Sergey I., Panov Vladimir I., Chris Van Haesendonck, Oreshkin Andrey I.
- Журнал: Nano Research
- Год издания: 2019
- Издательство: Tsinghua Univ Press
- Местоположение издательства: China
- DOI: 10.1007/s12274-019-2542-1
- Аннотация: The simultaneous formation of single domain (3×3) and multi domain (√7×√7)R(±19.1°) germanene phases on Al(111) surface in thesub-monolayer range was studied using scanning tunneling microscopy (STM) and density functional theory (DFT) based simulations.Experimental results revealed that both germanene phases nucleate and grow independently from each other and regardless of Al substratetemperature within significantly expanded range Ts = 27–200 °C. Our results unambiguously showed that STM images with hexagonalcontrast yield correct-resolved structure for both germanene phases, while honeycomb contrast is a result of an artificial tip-induced STMresolution. First-principles calculations suggested atomic models with strongly buckled germanene (2×2)/Al(111)(3×3) and (√3×√3)R30°/Al(111)(√7×√7)R(±19.1°) with one of eight and one of six Ge atoms protruding upward respectively, that consistently describe the experimentallyobserved STM images both for single and multi domain surface phases. According to the DFT based simulations both germanene (2×2) and(√3×√3)R30° superstructures have a stretched lattice strain with respect to the ideal free-standing germanene by 6.2% and 13.9%,respectively. Hence, numerous small domains separated by domain boundaries in the (√3×√3)R30°/Al(111)(√7×√7)R(±19.1°) germanenephase tend to reduce the surface energy and prevent the formation of extended single domains, in contrast to the (2×2)/Al(111)(3×3) phase.However, our experimental results showed that the nucleation and growth of germanene on Al(111) surface yield strong modifications of Alsurface even at room temperature (RT), which may be contributed to the formation of Al-Ge alloy due to Ge surface solid-states reactivitythat was ignored in recent studies. It is already evident from our present findings that the role of Al atoms in the formation of (3×3) and(√7×√7)R(±19.1°) germanene phases is worthy to be carefully studied in the future, which could be an important knowledge for large-quantityfabrication of germanene on aluminum.
- Добавил в систему: Орешкин Сергей Иванович