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Tunable Electronic and Topological Properties of Germanene by Functional Group Modification

School of Physics, University of Jinan, Jinan 250022, China
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Nanomaterials 2018, 8(3), 145; https://doi.org/10.3390/nano8030145
Received: 5 January 2018 / Revised: 2 March 2018 / Accepted: 2 March 2018 / Published: 6 March 2018
Electronic and topological properties of two-dimensional germanene modified by functional group X (X = H, F, OH, CH3) at full coverage are studied with first-principles calculation. Without considering the effect of spin-orbit coupling (SOC), all functionalized configurations become semiconductors, removing the Dirac cone at K point in pristine germanene. We also find that their band gaps can be especially well tuned by an external strain. When the SOC is switched on, GeX (X = H, CH3) is a normal insulator and strain leads to a phase transition to a topological insulator (TI) phase. However, GeX (X = F, OH) becomes a TI with a large gap of 0.19 eV for X = F and 0.24 eV for X = OH, even without external strains. More interestingly, when all these functionalized monolayers form a bilayer structure, semiconductor-metal states are observed. All these results suggest a possible route of modulating the electronic properties of germanene and promote applications in nanoelectronics. View Full-Text
Keywords: germanene; functional group; external strain; topological insulator germanene; functional group; external strain; topological insulator
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MDPI and ACS Style

Ren, C.-C.; Zhang, S.-F.; Ji, W.-X.; Zhang, C.-W.; Li, P.; Wang, P.-J. Tunable Electronic and Topological Properties of Germanene by Functional Group Modification. Nanomaterials 2018, 8, 145.

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