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 ($E_g=0.512eV$) and significant Rashba SOC effect (${\alpha }_R=2.819\text{ eVÅ}$). 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.