Kong Longjuan, Liu Liren, Chen Lan, Zhong Qing, Cheng Peng, Li Hui, Zhang Zhuhua, Wu Kehui
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Mechanics and Control of Mechanical Structures, and Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Nanoscale. 2019 Sep 7;11(33):15605-15611. doi: 10.1039/c9nr03792f. Epub 2019 Aug 12.
Two-dimensional boron (borophene) features structural polymorphs and distinct in-plane anisotropy, opening opportunities to achieve tailored electronic properties by intermixing different phases. Here, using scanning tunneling spectroscopy combined with first-principles calculations, delocalized one-dimensional nearly free electron states (NFE) in the (2,3) or β borophene sheet on the Ag(111) surface were observed. The NFE states emerge from a line defect in borophene, manifested as a structural unit of the (2,2) or χ sheet, which creates an in-plane potential well that shifts the states toward the Fermi level. The NFE states are held near the 2D plane of borophene, rather than in the vacuum region as observed in other nanostructures. Furthermore, borophene can provide a rare prototype to further study novel NFE behaviors, which may have potential applications in transport or field emission nanodevices based on boron.
二维硼（硼烯）具有结构多晶型和明显的面内各向异性，这为通过混合不同相来实现定制电子特性提供了机会。在此，利用扫描隧道光谱结合第一性原理计算，在Ag(111)表面的(2,3)或β硼烯片中观察到了离域的一维近自由电子态（NFE）。这些NFE态源自硼烯中的线缺陷，表现为(2,2)或χ片的结构单元，它产生了一个面内势阱，使这些态向费米能级移动。NFE态被限制在硼烯的二维平面附近，而不像在其他纳米结构中那样处于真空区域。此外，硼烯可以为进一步研究新型NFE行为提供一个罕见的原型，这可能在基于硼的输运或场发射纳米器件中具有潜在应用。
