LAUSR

Using density functional and many-body perturbation theories, we explore the strain and electric field effects on the electronic structures and optical properties of hexagonal arsenene (β-As) and antimonene (β-Sb). The calculations show that they can transform from indirect into direct bandgap semiconductors, and even semimetals under biaxial tensile strain and an electric field perpendicular to the layer. In particular, under a stronger electric field, their bandgaps gradually close owing to the field-induced motion of nearly free electron states. More interestingly, increasing the strain can significantly red-shift the optical absorption spectra and even enhance the optical absorption in the energy region of 1.2–2.2 eV (including infrared and partial visible light). Under a stronger electric field, their optical absorptions are enhanced and a large exciton binding energy can be retained. Such dramatic characteristics in the electronic structures and optical properties suggest great potential of β-As and β-Sb for novel electronic and optoelectronic devices.