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 eVÅ ). The topological phases, which originate from s-p x,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. • We predict that the ethynyl functionalized GaBi/InBi monolayers are topological insulators with large bandgap ( E g = 0.512 eV ) and significant Rashba SOC effect ( α R = 2.819 eVÅ ) . • We research the strain engineering and explain the change in topology phase through evolution of orbitals. • We study the significant Rashba SOC effect and the electric field impact. • The h -BN is found to be an ideal substrate for the growth of these QSH insulators.