金刚石纳米线氮空位色心的表面与尺寸效应

使用大规模自旋极化密度泛函理论计算研究了表面修饰和尺寸对金刚石纳米线(DNs)中氮空位(NV)色心的几何结构、 电子结构、 磁性和稳定性的影响. 理论上设计了几种不同的DNs, 这些DNs具有不同的表面修饰(干净、 氢化和氟化), 并且直径达数百个原子. 实验结果证明, 中性(NV⁰)和带1个负电荷(NV^-)的NV色心的电子结构不受半导体表面修饰和DNs直径大小的影响, 但NV色心的稳定性对这两个因素具有不同的响应. 此外, 研究中还发现, 由于DNs中存在圆柱形表面电偶极子层, 对DNs中掺杂的NV^-色心的稳定性, 表面改性诱导了不依赖尺寸的长程效应. 特别地, 对于n型氟化金刚石表面, 掺杂在DN中的NV^-色心可以稳定存在, 而对于p型氢化表面, NV⁰则相对更稳定. 因此, 表面修饰为控制金刚石纳米线中的NV色心的电子结构和稳定性提供了一种精确有效的调控方法.

Surface and Size Effects of Nitrogen-vacancy Centers in Diamond Nanowires

To control the electronic structures and stability of nitrogen-vacancy（NV） center in diamond is crucial for their practical applications. The surface and size effects on the structural， electronic， magnetic properties and stability of NV centers doped in diamond nanowires（DNs） were systematically investigated via large-scale spin-polarized density functional theory calculations. We theoretically design several types of DNs with different surface modifications（clean， hydrogenated and fluorinated） and the diameter sizes up to hundreds of atoms. It demonstrated that the electronic structures of neutral NV⁰ and negative NV^- centers are not affected by semiconducting surface modifications and diameter sizes of DNs， but the stability are sensitive to these two effects. Furthermore， we find that the surface modifications induce a size-independent and long-range effect on the stability of the NV^-center doped in DNs due to the cylindrical surface electric dipole layer in DNs. In particular， the NV^- center doped in DNs can be stabilized for n-type fluorinated diamond surfaces， while NV⁰ is relatively more stable for p-type hydrogenated surfaces. Therefore， surface modification provides a precise and effective way to control the electronic structures and stability of charged defects in semiconductors.