Strain-tunable electronic and transport properties of a BSb monolayer

It has been reported that monolayered BSb has excellent carrier mobility. In this work, we investigate the effect of strain on the electronic properties of a BSb monolayer and the transport properties of related devices based on density functional theory calculations combined with the nonequilibrium Green’s function method. We find that under biaxial tensile strain, the direct bandgap of the BSb monolayer continuously increases and turns to an indirect gap at strain strength ɛ = 7 . 2 % . The indirect gap is closed at ɛ = 10 . 1 % . Such a semiconductor–metal transition is caused by strain-induced change of orbital distribution in the BSb monolayer. Additionally, we investigate the transport properties of transistor devices based on monolayered BSb. In the output characteristics, a striking negative differential conductance is demonstrated. In the transfer characteristics, we find that the subthreshold swing and the ratio of maximum to minimum drain current can be enhanced by the tensile strain ɛ ≤ 5 % . These features can be understood from the strain-induced change of band gap and the effect of the gate and bias voltages on the effective barrier height in the channel region. Our findings indicate potential applications of BSb monolayer in nanoelectronics. • Tensile strain induces a direct to indirect bandgap transition in monolayered BSb. • Tensile strain causes a semiconductor–metal transition in BSb monolayer . • BSb-based transistor shows negative differential conductance. • Tensile strain ≤ 5% enhances the performance of BSb-based transistor.