搜索

x
中国物理学会期刊

双层硼烯纳米带的量子输运研究

CSTR: 32037.14.aps.71.20221304

Quantum transport properties of bilayer borophene nanoribbons

CSTR: 32037.14.aps.71.20221304
PDF
HTML
导出引用
  • 硼烯是继石墨烯以来很有潜力的新型二维材料, 本文采用格林函数方法结合Landauer-Büttiker公式, 着重研究了电极-中心区连接方式、层间跃迁和在位能无序对双层硼烯纳米带电荷输运的影响, 计算了双层硼烯纳米带的色散关系、透射谱以及电流-电压曲线. 计算结果表明: 双层硼烯纳米带均呈现金属行为, 该现象与电极-中心区连接方式、层间跃迁以及无序均无关, 定性解释了双层硼烯为金属的实验结果. 当左右电极为单层硼烯时, 体系透射谱不存在量子化电导平台, 相应的电流小于左右电极均为双层硼烯纳米带的情况. 电流与层间跃迁的关系依赖电极-中心区连接方式. 当左右电极为双层硼烯时, 随层间跃迁的增大, 电流先增大后减小; 当左右电极不相同时, 随层间跃迁的增大, 电流先迅速增大而后达到饱和; 当左右电极为上(下)层硼烯时, 随层间跃迁的增大, 电流振荡下降(上升). 最后发现双层硼烯纳米带的输运性能随无序强度的增大而减弱.

     

    Since British scientists Geim et al. (Novoselov K S, Geim A K, Morozov S V, Jiang D, Zhang Y, Dubonos S V, Grigorieva I V, Firsov A A 2004 Science 306 666) successfully peeded off single-layer graphene from multilayer graphite for the first time in 2004, two-dimensional materials have quickly caught the attention of scientists. Owing to its honeycomb structure, graphene exhibits many novel mechanical, thermal, electrical, and magnetic properties, which have attracted great attention and have broad application prospects in electronic devices and other fields. With the further development of research, more and more two-dimensional materials have been discovered successively, including silicene, germanene, and borylene. These two-dimensional materials have various excellent properties like graphene. Boron is one of the nearest-neighbor elements of carbon, it has proved to be able to form borophene, which has a lot of novel properties, including superconductivity and Dirac fermions. Several polymorphs of monolayer borophene have been synthesized on different metal surfaces, such as Au, Cu, Ag, Ir and Al. Using the nonequilibrium Green's function, we investigate the electronic transport properties of bilayer borophene which was synthesized recently. We first calculate the transmission spectra of different interlayer transition strengths when the electrode has two layers, then we calculate the currents of bilayer borophene under different voltages when the electrode has two layers, which both show bilayer borophene is metallic. With the enhancement of the interlayer transition strength, its conductivity first increases and then decays. We try to change the layer number of electrode. In scheme two, the left electrode is the lower half of the bilayer borophene while the right electrode is the upper half of the bilayer borophene. In scheme three both electrodes are the lower half of the bilayer borophene. In scheme four, both electrodes are the upper half of the bilayer borophene. In scheme five, the left electrode is the upper half of the bilayer borophene while the right electrode is the lower half of the bilayer borophene. We discover that the current decays greatly when the electrode is just one layer. For scheme three and scheme four, both left electrode and right electrode are the lower half of the bilayer borophene or the upper half of the bilayer borophene, the current will rise or decline in volatility. For scheme two or scheme five, the electrode is unsymmetrical, we find that the current will reach a maximum when interlayer transition increases. The reason for the above phenomenon is that the electrical conductivity of the upper half of the bilayer borophene is higher than that of the lower half, which causes the electrons of the lower half of the bilayer borophene to tunnel to the upper half so that the conductivity of bilayer borophene is enhanced when the interlayer transition strength is weak. However, when the interlayer transition strength is great, the frequent interlayer transition of electrons results in large scattering, thus causing its conductivity to decay. Finally, we consider the influence of the on-site disorder on the transport properties of the bilayer borophene, finding that its transport capability will be declined by increasing the disorder strength.

     

    目录

    /

    返回文章
    返回