Large gap two-dimensional topological insulators with prominent Rashba effect in ethynyl functionalized III-Bi Buckled-Honeycomb monolayers

Abstract Recently, two-dimensional topological insulators have attracted extensive attention because of their excellent electronic transport performance and easy integration into electronic devices. However, the small bandgap limits their room-temperature application. Based on first-principles calculations, we predict that the ethynyl functionalized GaBi/InBi monolayers are topological insulators with large bandgap ( E g = 0.512 e V ) and significant Rashba SOC effect ( α R = 2.819  eVA ). The topological phases, which originate from s-px,y band inversion induced by chemical bonding, can be maintained within the large-range biaxial strain. Additionally, the h-BN is found to be an ideal substrate for the growth of these QSH insulators. These findings indicate that the ethynyl functionalized Ⅲ-Bi monolayers are expected to be candidate materials for spintronics and quantum computing. These findings indicate that the ethynyl functionalized Ⅲ-Bi monolayers are expected to be candidate materials for spintronics and quantum computing.