Driving a GaAs film to a large-gap topological insulator by tensile strain

Search for materials with a large nontrivial band gap is quite crucial for the realization of the devices using quantum spin Hall (QSH) effects. From first-principles calculations combined with a tight-binding (TB) model, we demonstrate that a trivial GaAs film with atomic thickness can be driven to a topological insulator with a sizable band gap by tensile strain. The strain-induced band inversion is responsible for the electronic structure transition. The nontrivial band gap due to spin-orbital coupling (SOC) is about 257 meV, sufficiently larger for the realization of QSH states at room temperature. This work suggests a possible route to the fabrication of QSH-based devices using the well-developed GaAs technology.