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arXiv · 2412.14582

Electronic and Optical Properties of Ta$_2$NiSe$_5$ Monolayer: A First-principles Study

Miaomiao Guo·Yuanchang Li
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Abstract

The crystal structure, stability, electronic and optical properties of the Ta$_2$NiSe$_5$ monolayer have been investigated using first-principles calculations in combination with the Bethe-Salpeter equation. The results show that it is feasible to directly exfoliate a Ta$_2$NiSe$_5$ monolayer from the low-temperature monoclinic phase. The monolayer is stable and behaves as a normal narrow-gap semiconductor with neither spontaneous excitons nor non-trivial topology. Despite the quasi-particle and optical gaps of only 266 and 200 meV, respectively, its optically-active exciton has a binding energy up to 66 meV and can exist at room temperature. This makes it valuable for applications in infrared photodetection, especially its inherent in-plane anisotropy adds to its value in polarization sensing. It is also found that the inclusion of spin-orbit coupling is theoretically necessary to properly elucidate the optical and excitonic properties of monolayer.

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Miaomiao Guo, Yuanchang Li. 2024-12-19. Electronic and Optical Properties of Ta$_2$NiSe$_5$ Monolayer: A First-principles Study. https://doi.org/10.1063/5.0231169

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