Phonon-mediated superconductivity in electron-doped monolayer InSe: A first-principles investigation

In this study, we investigated the electron-phonon coupling and superconductivity properties of an electron-doped indium selenide (InSe) monolayer for the first time. Electron doping at 0.1 e/cell induced significant phonon softening of the acoustic ZA mode, a lower frequency E″ mode, and higher frequency A′1 mode, which were responsible for the electron-phonon coupling. Under greater doping at 0.2 e/cell, the electronic density of states at the Fermi level increased remarkably and the two Fermi sheets around Γ and M expanded. The transition temperature increased to 3.41 K according to the McMillan-Allen-Dynes formula, which is higher than that of 1.7 K in silicene with doping at 0.44 e/atom and 2.85 K in Na-intercalated MoS2 bilayers calculated using the same method. The phonon-mediated superconductivity predicted in this study combined with the topologically nontrivial characteristics reported previously suggest that few-layer InSe is a potential platform for achieving topologically superconductivity in two dimensions.