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Ultrahigh electron mobility induced by strain engineering in directly semiconducting monolayer Bi$_2$TeSe$_2$

Abstract

The successfully commercial applications as thermoelectric devices and the exotic electronic properties as topological insulators of bismuth telluride (Bi$_2$Te$_3$) and bismuth selenide (Bi$_2$Se$_3$) have stimulated the research interests on Bi$_2$Se$_3$/Bi$_2$Te$_3$-based chemical compounds. Based on the first-principles calculations, we investigate the electronic, optical, vibrational and transport properties of new monolayer Bi$_2$TeSe$_2$ obtained by transmuting one Se atom into its neighboring Te atom in the same group from Bi$_2$Se$_3$. We find that the monolayer Bi$_2$TeSe$_2$ maintains stable hexagonal structure up to $700$ K. Monolayer Bi$_2$TeSe$_2$ possesses a direct bandgap of $0.29$ eV due to the strong spin-orbit coupling effects, and the directly semiconducting maintains for strains in a moderate range. The optical absorption covers a wide range from green region to ultraviolet region, which may lead to applications in optoelectronic devices like saturable absorbers. An extremely high electron mobility of $21353$ cm$^2$V$^{-1}$s$^{-1}$ along zigzag direction can be achieved by strain engineering with $-6\%$ compressive strain, which is nearly ten times larger than its intrinsic mobility. These indicate that monolayer Bi$_2$TeSe$_2$ is a promising candidate for future high-speed (opto)electronic devices.

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Publication details

The article was received on 07 Jul 2019, accepted on 28 Sep 2019 and first published on 30 Sep 2019


Article type: Paper
DOI: 10.1039/C9NR05725K
Nanoscale, 2019, Accepted Manuscript

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    Ultrahigh electron mobility induced by strain engineering in directly semiconducting monolayer Bi$_2$TeSe$_2$

    Z. Lu, Y. Wu, Y. Xu, C. Ma, Y. Chen, K. Xu, H. Zhang, H. Zhu and Z. Fang, Nanoscale, 2019, Accepted Manuscript , DOI: 10.1039/C9NR05725K

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