College of Physics and Information Technology, Shaanxi Normal University, Xian, 710062 Shaanxi, PR China.
Nanoscale. 2011 Oct 5;3(10):4330-8. doi: 10.1039/c1nr10594a. Epub 2011 Sep 7.
We perform a spin polarized density-functional theory (DFT) study of the electronic and magnetic properties of pristine and chemically doped germanene nanoribbons (GeNRs) with different widths. It is found that the Ge atom at the ribbon edge always prefers to be substituted by an impurity atom. Our study reveals that a single N or B atom substitution induces a semiconducting-metal transition in armchair oriented germanene nanoribbons (AGeNRs) as evidenced by the appearance of a half-filled band with less dispersion; however, N and B co-doping at the ribbon edges only modifies their band gaps, due to the accomplishment of an effective charge compensation. A single N or B atom substitution usually turns antiferromagnetic (AFM) semiconducting zigzag germanene nanoribbons (ZGeNRs) into ferromagnetic (FM) semiconductors. This AFM-FM transition is attributed mainly to the perturbation of π and π states localized at the doped edge. Double atom substitutions (regardless of N-N, B-B or N-B configurations) at the edges of ZGeNRs removes the spin-polarization at both edges and transforms them into non-magnetic (NM) semiconductors. Moreover, it is interesting that some single atom doped ZGeNRs can exhibit a FM half-metallic character with 100% spin-polarization at the Fermi level. Our results suggest that doped AGeNRs and ZGeNRs have potential applications in Ge-based nanoelectronics, such as field effect transistors (FETs), negative differential resistance (NDR) and spin filter (SF) devices.
我们对原始和化学掺杂的具有不同宽度的锗烯纳米带(GeNRs)的电子和磁性质进行了自旋极化密度泛函理论(DFT)研究。发现边缘的锗原子总是倾向于被杂质原子取代。我们的研究表明,单个 N 或 B 原子取代会导致扶手椅取向的锗烯纳米带(AGeNRs)发生半导体-金属转变,这表现为具有较小色散的半满带的出现;然而,边缘处的 N 和 B 共掺杂仅会改变它们的带隙,因为实现了有效的电荷补偿。单个 N 或 B 原子取代通常会使反铁磁(AFM)半导体锯齿形锗烯纳米带(ZGeNRs)转变为铁磁(FM)半导体。这种 AFM-FM 转变主要归因于掺杂边缘处局部化的 π 和 π 态的扰动。ZGeNRs 边缘处的双原子取代(无论 N-N、B-B 还是 N-B 构型)都会在两个边缘处消除自旋极化,并将其转变为非磁性(NM)半导体。此外,有趣的是,一些单原子掺杂的 ZGeNRs 可以表现出 FM 半金属特性,在费米能级处具有 100%的自旋极化。我们的结果表明,掺杂的 AGeNRs 和 ZGeNRs 在基于 Ge 的纳米电子学中具有潜在的应用,例如场效应晶体管(FET)、负微分电阻(NDR)和自旋滤波器(SF)器件。