Low-Pressure CVD Synthesis of Tetragonal Borophene Single-Crystalline Sheets with High Ambient Stability

Tetragonal borophene sheetsby the LPCVD method exhibithigh ambient stability, and they should have promising future in coldcathode applications. Being a typical graphene-like two-dimensional (2D) material,borophenehas received a lot of attention due to its low density, high electronmobility, large Young's modulus, and good chemical stability.Compared with the corresponding bulk counterparts, 2D borophene haslarger specific surface area, higher conductivity, and smaller workfunction, finding potential applications in high-speed transistors,optoelectronic detection, field emission (FE), and mechanical enforcementareas. In this paper, 2D tetragonal borophene sheets with high ambientstability have been successfully fabricated on the surface of 1 cm(2) copper foil using a developed low-pressure chemical vapordeposition (LPCVD) method. The vapor-solid mechanism was usedto comprehend the formation of the tetragonal borophene sheets. Theelectrical conductivity of individual borophene sheets ranged from4 to 5 x 10(-4) S/cm, and the band gap was about2.1 eV, suggesting their narrow semiconductive nature. Also, the maximumFE current of individual borophene sheets was close to 1 mu A,and their emission properties enhanced with the decreasing sheet thickness,comparable to many other nanomaterials with excellent FE performances.More interestingly, individual borophene sheets were found to retaingood enough electrical transport and FE behaviors even if they experiencedseveral days' atmospheric conservations. Our research resultssuggest that the LPCVD-grown borophene may be a promising buildingblock for constructing high-performance nanodevices with good ambientstability.

Automated summary

Tetragonal borophene sheets with high ambient stability were successfully fabricated by the LPCVD method. Compared with bulk counterparts, 2D borophene has potential applications in high-speed transistors, optoelectronic detection, field emission, and mechanical enforcement areas. The research suggests that LPCVD-grown borophene may be a promising building block for constructing high-performance nanodevices with good ambient stability.