Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States.
J Am Chem Soc. 2017 Nov 29;139(47):17181-17185. doi: 10.1021/jacs.7b10329. Epub 2017 Nov 14.
Recently discovered two-dimensional (2D) boron polymorphs, collectively tagged borophene, are all metallic with high free charge carrier concentration, pointing toward the possibility of supporting plasmons. Ab initio linear response computations of the dielectric function allow one to calculate the plasmon frequencies (ω) in the selected example structures of boron layers. The results show that the electrons in these sheets indeed mimic a 2D electron gas, and their plasmon dispersion in the small wavevector (q) limit accurately follows the signature dependence ω ∝ √q. The plasmon frequencies that are not damped by single-particle excitations do reach the near-infrared and even visible regions, making borophene the first material with 2D plasmons at such high frequencies, notably with no necessity for doping. The existence of several phases (polymorphs), with varying degree of metallicity and anisotropy, can further permit the fine-tuning of plasmon behaviors in borophene, potentially a tantalizing material with utility in nanoplasmonics.
最近发现的两种二维（2D）硼同素异形体，统称为硼烯，均为金属且具有高的自由载流子浓度，这表明它们有可能支持等离激元。通过对介电函数的从头算线性响应计算，可以计算所选硼层结构中的等离激元频率（ω）。结果表明，这些薄片中的电子确实模拟了二维电子气，并且它们在小波矢（q）极限下的等离激元色散准确地遵循ω∝√q的特征依赖性。不受单粒子激发阻尼的等离激元频率甚至可以达到近红外区，甚至可见光区，这使得硼烯成为第一种具有如此高频率的二维等离激元的材料，尤其是不需要掺杂。几种相（同素异形体）的存在，具有不同程度的金属性和各向异性，可以进一步微调硼烯中的等离激元行为，这种材料具有纳米等离激元学的应用潜力，是一种很有吸引力的材料。
