Electron-phonon interaction in a Ca2N monolayer: Intrinsic mobility of electrene

The electron-phonon (e-ph) interaction in Ca2N monolayer, the first electrene material with two-dimensional (2D) electron gas floating in free space, is expected to be very weak, which can be used to design weak-scattering transport channels. Therefore, it is highly desirable to quantitatively evaluate the carrier mobility of this electrene material. In this study, the e-ph interaction in Ca2N monolayer is investigated by using a precise Wannier interpolation-based first-principles technique. The calculated e-ph coupling matrix elements of Ca2N monolayer are indeed small compared with other 2D materials such as graphene, which leads to an intrinsic mobility of 189 cm(2) V-1 s(-1), which is much higher than those of conventional metals. Other factors affecting mobility are discussed in a comparison with graphene. It is predicted that, based on a momentum mismatch mechanism, mobility of the Ca2N monolayer can be increased further to above 3000 cm(2) V-1 s(-1) via hole doping. Our results confirm that Ca2N electrene is a promising electronic material.