Enhanced electron-phonon coupling and superconductivity in BC2N monolayer via lithium deposition: A first principles investigation

ABSTRACT Two dimensional (2D) superconductors are important both for the basic understanding of paring mechanism and potential applications in nanosuperconducting quantum interference devices. In this work, we explore the phonon-mediated superconductivity of hole doped and Lithium-deposited monolayer BC2N by first-principles calculations. Our results reveal that the hole doped planar BC2N can not superconduct due to a small electron-phonon coupling constant ( λ = 0.07 ). When lithium is deposited on the monolayer, the EPC constant are significantly enhanced to 0.52 and the superconducting transition temperature Tc is determined to be 3.58 K. Because more phonons, in paticular, the out-of-plane modes are triggered to participate in the EPC process, The Tc is higher than 1.4 K of Ca-deposited graphene, 1.3 K of Li-deposited stanene and 3 K of doped WS2 and NbSe2. It is also found that tensile biaxial strain weaken the EPC and leads to a decreased superconducting transition temperature. Our findings will provide a new guideline for designing novel 2D superconductors and enrich the potential application of 2D BC2N.