Hansson Anders, Mota Fernando de B, Rivelino Roberto
Instituto de Física, Universidade Federal da Bahia, 40210-340, Salvador, Bahia, Brazil.
Phys Chem Chem Phys. 2014 Jul 28;16(28):14473-8. doi: 10.1039/c3cp55235g.
After the success of graphene, several two-dimensional (2D) layers have been proposed and investigated both theoretically and experimentally in order to evaluate their structural stability and possible applications of these unusual materials in electronics. Except for graphene, only silicon and germanium were predicted to form semi-metallic honeycomb monolayers, while most of the binary graphene-like compounds are all semiconductors. These predictions have been corroborated for several 2D structures experimentally synthesized. Considering the possibility of finding other candidates in this realm, exhibiting exceptional electron mobility, we have explored low-dimensional silicon-boron compounds containing planar sp(2)-bonding silicon atoms, through first-principles density-functional theory calculations. We have demonstrated that the so-called h-SiB sheet, which is a structural analogue of 2D honeycomb binary compounds, exhibits good structural stability, compared to the structure of silicene, for example, and predicted that this structure is also able to roll up into thermally stable single-walled silicon-boron nanotubes. The h-SiB sheet exhibits a delocalized charge density like in graphene, but the partially filled π band and two highest occupied σ bands are above the Fermi level, leading to the metallic behaviour of this SiB sheet. In this sense, we perform first-principles electron transport calculations, based on the nonequilibrium Green's function formalism, which has demonstrated that h-SiB exhibits higher transmission around the Fermi energy than the transmission in graphene. Our results indicate the unusual conductivity of this new material and open up new possibilities for the realization of metallic graphene-like systems for electronic transport in low dimensions.
在石墨烯取得成功之后，人们提出并从理论和实验两方面研究了几种二维（2D）层，以评估其结构稳定性以及这些特殊材料在电子学中的潜在应用。除了石墨烯之外，只有硅和锗被预测能形成半金属蜂窝状单分子层，而大多数类石墨烯二元化合物都是半导体。对于几种通过实验合成的二维结构，这些预测已得到证实。考虑到在这一领域找到其他具有卓越电子迁移率的候选材料的可能性，我们通过第一性原理密度泛函理论计算，探索了含有平面sp(2)键合硅原子的低维硅硼化合物。我们已经证明，所谓的h-SiB片层，它是二维蜂窝状二元化合物的结构类似物，与硅烯结构相比，具有良好的结构稳定性，并预测该结构还能够卷成热稳定的单壁硅硼纳米管。h-SiB片层表现出与石墨烯类似的离域电荷密度，但部分填充的π带和两个最高占据的σ带位于费米能级之上，导致该SiB片层具有金属特性。从这个意义上说，我们基于非平衡格林函数形式进行了第一性原理电子输运计算，结果表明h-SiB在费米能量附近的传输率高于石墨烯中的传输率。我们的结果表明了这种新材料具有非同寻常的导电性，并为实现用于低维电子输运的类金属石墨烯系统开辟了新的可能性。
