Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798.
Phys Chem Chem Phys. 2012 Jan 21;14(3):1166-74. doi: 10.1039/c1cp22262g. Epub 2011 Nov 30.
Germanium nanowires (GeNWs) with single, double, quadruple and octuple surface dangling bonds (SDBs) are investigated using density-functional-theory calculations. We show that single SDB defected GeNWs remain semiconducting as their non-defected form while double or multiple SDB defects result in either semiconducting or metallic GeNWs, depending on the defect's locations on the surface. More importantly, we show that the electronic properties of surface defected GeNWs can also be fine-tuned by applying tensile and compressive strains. Upon the right loading, the surface defected GeNWs become half-metallic. In addition, we determine that the surface defected GeNWs can be classified into three classes: (1) GeNWs with zero magnetic moment, which are either metallic or semiconducting; (2) GeNWs with net magnetic moments equal to the number of SDBs, which are semiconducting with distinct spin-up and spin-down configurations; and (3) GeNWs with net magnetic moments significantly lower than the number of SDBs. We also find that only the defected GeNWs that fall under (3) are potentially half-metallic. Our results predict that half-metallic GeNWs can be obtained via engineering of the surface defects and the structures without the presence of impurity dopants.
使用密度泛函理论计算研究了具有单个、双个、四个和八个表面悬挂键（SDB）的锗纳米线（GeNWs）。我们表明，单个 SDB 缺陷的 GeNWs 保持半导体特性，与其无缺陷形式相同，而双个或多个 SDB 缺陷则导致半导体或金属 GeNWs，这取决于表面上缺陷的位置。更重要的是，我们表明，表面缺陷的 GeNWs 的电子性质也可以通过施加拉伸和压缩应变来微调。在适当的加载下，表面缺陷的 GeNWs 变为半金属。此外，我们确定表面缺陷的 GeNWs 可以分为三类：（1）具有零磁矩的 GeNWs，其为金属或半导体；（2）具有 SDB 数目的净磁矩的 GeNWs，其具有明显的自旋向上和自旋向下配置的半导体；（3）具有显著低于 SDB 数目的净磁矩的 GeNWs。我们还发现，只有属于（3）的缺陷 GeNWs 才有可能是半金属。我们的结果表明，可以通过表面缺陷和结构的工程设计而无需杂质掺杂剂来获得半金属 GeNWs。
