掺杂对磷烯纳米带电子性质的调制

发布时间：2019-01-01 10:20

【摘要】：2014年,实验中制备出一种新型的二维材料——磷烯,因为其具有极高的开关比、载流子迁移率和天然的直接带隙,在场效应晶体管、光电子器件等方面展现出广阔的应用前景,磷烯很快成为目前纳米物理领域研究的一种热点材料。考虑到磷烯在电子器件领域实际应用中的需求,边缘效应和掺杂效应对器件电子性质的影响极为重要。本文我们采用第一性原理方法研究了常见边缘官能团修饰的锯齿型磷烯纳米带的重构和电子性质以及锯齿型磷烯纳米带在过渡金属元素掺杂下的磁性调制。(1)我们采用基于密度泛函理论的第一性原理方法,研究了在边缘官能团H、F、O、S和OH修饰的磷烯纳米带中相邻官能团的协同作用对其边缘形貌和电子性质的影响。我们发现,这种协同作用对于边缘H(F)修饰时并不明显,但O(S)修饰时却在磷烯纳米带边缘形成重构。这种重构来源于边缘相邻O(S)原子间的排斥以及边缘原子与官能团间的p态耦合导致的磷骨架畸变。O(S)修饰的磷烯纳米带是半导体,相比H修饰,其带隙更大,同时在导带底附近引进一个新的输运通道,而且O修饰能够降低电子有效质量。OH修饰的锯齿型磷烯纳米带由于同边缘OH官能团O-H键指向不同,边缘也形成重构。相比H修饰,OH修饰的带隙和电子有效质量都非常相近,但是空穴有效质量更大。(2)我们采用基于密度泛函理论的第一性原理方法,通过Fe、Co、Ni对锯齿型磷烯纳米带进行3d过渡金属的掺杂,来探讨尺寸效应和边缘效应对局域磁矩及磁矩调制的影响。研究发现,对于这三种过渡金属掺杂的稳定位点都在条带内部,且掺杂位点与边缘的距离大于3条锯齿型链时,掺杂位置不再受到边缘的影响。Co掺杂不能引入非零磁矩,而Fe和Ni引起1μB的局域磁矩。外加应变时,Co、Fe、Ni掺杂纳米带的局域磁矩保持不变。Fe、Ni掺杂磷烯纳米带的局域磁矩源自过渡金属3d轨道杂化。
[Abstract]:In 2014, a new two-dimensional material, phosphorene, was prepared in the experiment because of its high switching ratio, carrier mobility and natural direct band gap, field effect transistors, optoelectronic devices and so on. Phosphorene has quickly become a hot material in the field of nanometer physics. Considering the practical application of phosphorene in electronic devices, the influence of edge effect and doping effect on the electronic properties of the device is very important. In this paper, we have studied the reconstruction and electronic properties of the common edge-modified zigzag phosphorene nanoribbons by first-principles method and the magnetic modulation of the zigzag phosphorene nanoribbons doped with transition metal elements. (1) We use the first principle method based on density functional theory, The effect of the synergetic effect of adjacent functional groups on the edge morphology and electronic properties of phosphorene nanobelts modified with OH and HfFO _ (O) O _ (S) was studied. We found that the synergistic effect was not obvious for the edge H (F) modification, but the O (S) modification resulted in the reconstruction at the edge of the phosphorene nanobelts. This reconstruction comes from the repulsion between adjacent O (S) atoms at the edge and the p-state coupling between the edge atoms and the functional groups. The phosphorene nanobelts modified by. O (S) are semiconductors, and the band gap is larger than that of H modification. At the same time, a new transport channel is introduced near the bottom of the conduction band, and O modification can reduce the effective mass of the electron. The OH modified zigzag phosphorene nanospheres have different O-H bond points at the same edge of the OH functional group, and the edges are also reconstructed. Compared with H modification, the band gap and electron effective mass of OH modification are very similar, but the effective mass of hole is much larger. (2) We adopt the first principle method based on density functional theory and Fe,Co,. The effect of size effect and edge effect on local magnetic moment and magnetic moment modulation was investigated by doping sawtooth phosphorene nanoribbons with 3D transition metal by Ni. It is found that the doping position is no longer affected by the edge when the distance between the doping site and the edge is greater than three zigzag chains, and the Co doping can not introduce non-zero magnetic moment. The local magnetic moment of 1 渭 B is induced by Fe and Ni. The local magnetic moments of Co,Fe,Ni doped nanobelts remain unchanged when the strain is applied. The local magnetic moments of Fe,Ni doped phosphene nanobelts are derived from the transition metal 3D orbital hybrid.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O469;TB383.1

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