Cai Bo, Zhang Shengli, Hu Ziyu, Hu Yonghong, Zou Yousheng, Zeng Haibo
Institute of Optoelectronics & Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Phys Chem Chem Phys. 2015 May 21;17(19):12634-8. doi: 10.1039/c5cp00563a.
Dirac materials have attracted great interest for both fundamental research and electronic devices due to their unique band structures, but the usual near zero bandgap of graphene results in a poor on-off ratio in the corresponding transistors. Here, we report on tinene, monolayer gray tin, as a new two-dimensional material with both Dirac characteristics and a remarkable 72 meV bandgap based on density functional theory calculations. Compared with silicene and germanene, tinene has a similar hexagonal honeycomb monolayer structure, but it has an obviously larger buckling height (∼0.70 Å). Interestingly, such a moderate buckling structure results in phonon dispersion without appreciable imaginary modes, indicating the strong dynamic stability of tinene. Significantly, a distinct transformation is discovered from the band structure that six Dirac cones would appear at high symmetry K points in the first Brillouin zone when gray tin is thinned from the bulk to monolayer, but a bandgap as large as 72 meV is still preserved. Considering the recent successful realization of silicene and germanene with a similar structure, the predicted stable tinene with Dirac characteristics and a suitable bandgap is a possibility for the "more than Moore" materials and devices.
由于其独特的能带结构，狄拉克材料在基础研究和电子器件领域都引起了极大的关注。然而，石墨烯通常近乎零的带隙导致相应晶体管的开关比很差。在此，我们基于密度泛函理论计算报告了单层灰锡烯作为一种兼具狄拉克特性和显著72毫电子伏特带隙的新型二维材料。与硅烯和锗烯相比，锡烯具有类似的六角蜂窝状单层结构，但具有明显更大的起伏高度（约0.70埃）。有趣的是，这种适度的起伏结构导致声子色散且没有明显的虚模，这表明锡烯具有很强的动态稳定性。值得注意的是，从能带结构中发现了一个明显的转变：当灰锡从体相减薄到单层时，在第一布里渊区的高对称K点会出现六个狄拉克锥，但仍保留高达72毫电子伏特的带隙。考虑到近期具有类似结构的硅烯和锗烯已成功实现，预测具有狄拉克特性和合适带隙的稳定锡烯有可能成为“超越摩尔”的材料和器件。
