Department of Microelectronics, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, PR China.
Sci Rep. 2016 Nov 29;6:38009. doi: 10.1038/srep38009.
In this paper, phosphorene nanoribbons (PNRs) are theoretically studied using a multiscale simulation flow from the ab initio level to the tight binding (TB) level. The scaling effects of both armchair PNRs (aPNRs) and zigzag PNRs (zPNRs) from material properties to device properties are explored. The much larger effective mass of holes compared to that of electrons in zPNR is responsible for its asymmetric transport. However, in aPNR, not only the effective mass difference but also the non-equal density of state (DOS) distributions near valence band maximum (VBM) and conduction band minimum (CBM) lead to the asymmetric transport. This non-equal distribution phenomenon is caused by energy band degeneracies near the VBM. Based on these two different mechanisms, PNRs' asymmetric transport characteristics at the device level are explained, and it is shown that this behaviour can be ameliorated well by reducing the ribbon width in an aPNR MOSFET. Calculation results also indicate that aPNR's effective mass is comparable to that of a graphene nanoribbon (GNR) at the same bandgap; however, aPNR's band gap variation is more stable and regular than that of GNR, making it a good candidate for use in low-dimensional nano devices.
本文采用从第一性原理到紧束缚的多尺度模拟方法，对磷烯纳米带（PNRs）进行了理论研究。从材料特性到器件特性，探讨了扶手椅型 PNRs（aPNRs）和锯齿型 PNRs（zPNRs）的标度效应。与 zPNR 中的电子相比，zPNR 中空穴的有效质量大得多，这导致了其非对称输运。然而，在 aPNR 中，不仅有效质量差，而且价带顶（VBM）和导带底（CBM）附近的态密度（DOS）分布也不相等，导致了非对称输运。这种非均匀分布现象是由 VBM 附近的能带简并引起的。基于这两种不同的机制，解释了器件级 PNRs 非对称输运特性，结果表明，通过减小 aPNR MOSFET 的带宽度，可以很好地改善这种行为。计算结果还表明，在相同带隙下，aPNR 的有效质量可与石墨烯纳米带（GNR）相媲美；然而，aPNR 的能带隙变化比 GNR 更稳定和规则，使其成为用于低维纳米器件的良好候选材料。
