Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA.
Angew Chem Int Ed Engl. 2017 Nov 27;56(48):15421-15426. doi: 10.1002/anie.201705459. Epub 2017 Oct 25.
Boron nanostructures are easily charged but how charge carriers affect their structural stability is unknown. We combined cluster expansion methods with first-principles calculations to analyze the dependence of the preferred structure of two-dimensional (2D) boron, or "borophene", on charge doping controlled by a gate voltage. At a reasonable doping level of 3.12×10 cm , the hollow hexagon concentration in the ground state of 2D boron increases to 1/7 from 1/8 in its charge-neutral state. The numerical result for the dependence of hollow hexagon concentration on the doping level is well described by an analytical method based on an electron-counting rule. Aside from in-plane electronic bonding, the hybridization among out-of-plane boron orbitals is crucial for determining the relative stability of different sheets at a given doping level. Our results offer new insight into the stability mechanism of 2D boron and open new ways for the control of the lattice structure during formation.
硼纳米结构很容易带电，但电荷载流子如何影响其结构稳定性尚不清楚。我们结合团簇展开方法和第一性原理计算来分析二维（2D）硼，或“硼烯”，在栅极电压控制的电荷掺杂下的优先结构对其的依赖关系。在合理的掺杂水平 3.12×10 cm 下，2D 硼的基态中空六边形浓度从电荷中性状态的 1/8 增加到 1/7。基于电子计数规则的分析方法很好地描述了中空六边形浓度对掺杂水平的依赖关系的数值结果。除了面内电子键合之外，面外硼轨道之间的杂化对于在给定掺杂水平下不同片层的相对稳定性至关重要。我们的结果为 2D 硼的稳定性机制提供了新的见解，并为形成过程中晶格结构的控制开辟了新途径。
