Bilayer Borophenes Exhibit Silicon‐Like Bandgap and Carrier Mobilities

• Published in: Advanced functional materials 2024-11, Vol.34 (46), p.n/a
• Main Authors: Xu, Ying, Wang, Zhenxian, Xuan, Xiaoyu, Zhang, Zhuhua, Guo, Wanlin
• Format: Article
• Language: English
• Subjects: Absorptivity; bilayer borophene; Bilayers; Borophene; Bulk density; Electron mobility; Energy gap; First principles; Graphene; Interlayers; Metal sheets; Nanomaterials; optical absorption; Optical properties; semiconductor; Silicon; Two dimensional materials
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202407952

Borophene, a boron analogue of graphene, is typically metallic, while all bulk boron phases are insulating. Here, we predict by first‐principles calculations that recently synthesized bilayer borophene, being suggested to be composed of two stacked v1/12 sheets, is a semiconductor with a bandgap of 1.13 eV, almost the same as that of silicon. It is shown that the stacking mode between two boron sheets as well as the density and pattern of the interlayer boron‐boron (B─B) bonds are the key factors for opening the bandgap in the otherwise metallic boron sheet. Moreover, the bilayer borophene exhibits electron mobility of 878.6 cm2 V−1 s−1 and a significantly higher optical absorption coefficient in the visible region than silicon. These excellent electronic and optical properties hosted in a two atom‐thick space, together with high thermal and mechanical stability, position the bilayer borophene as a promising nanomaterial for maintaining the miniaturization of electronics. The v1/12 bilayer borophene opens a bandgap through a synergy among the number and pattern of interlayer B─B bonds as well as the stacking mode between two v1/12 sheets. Compared with silicon, the v1/12 bilayer exhibits a nearly identical bandgap, comparable electron carrier density, and significantly higher optical absorption coefficient in the visible region.