Optical response of Te-based monolayer materials from first principles

Using density functional theory combined with nonequilibrium Green's function, the photocurrent induced by the photogalvanic effect of two phases of Te-based monolayer materials is calculated along both their zigzag and armchair directions under the irradiation of the linearly polarized light. Results show that the photocurrent has a sinusoidal shape with regard to the polarization angle of the light at all simulated bias voltages for different photon energies. A photocurrent peak for α-Te and β-Te is at the photon energy of around 1.4 and 1.8 eV, respectively. Furthermore, for α-Te the phase of the photocurrent vs the polarization angle curve reserves when the photon energy increases, while for β-Te the phase remains unchanged in our simulated photon energy range. The different optical responses of the two phases of Te-based monolayer materials along different directions make them have potential applications in various aspects of optoelectronics.