First principles studies of the electronic and optical properties of two-dimensional arsenic-phosphorous (2D-As-P) compounds*

We modeled 2D hybrid systems based on arsenene and phosphorene, comprising one hexagonal array and three possible orthorhombic arrangements. From phonon spectra we assured the dynamical stability. The computatuon of elastic constants and the cohesive energies ssured the mechanical and thermodynamic stabilities respectively. We also studied the electronic and optical properties. The band structures suggest high mobilities of charge carriers as the ones observed in phosphorene. The computation of band gap was performed by using the GW approximation. For the hexagonal structure, the indirect band gap was 3.63 eV, laying in the limit of visible spectrum and near ultraviolet. Conversely, the two stable orthorhombic structures show direct band gaps of 1.84 and 2.39 eV respectively, inside the visible range, allowing several applications in optoelectronic devices. To study the optical properties, we computed the dielectric function imaginary part within the BSE approach, obtaining exciton binding energies in the range between 550 and 660 meV, favorable to avoid recombination processes. We clalculated the absorption coefficient, which reveals strong absorption in the infrared and visible spectra. From our calculations, it can be established that the 2D-As-P systems are good candidates for several technological applications.

We acknowledge DGAPA-UNAM projects IN101523, IA100624, IG101124 and IN105722, and the LANCAD-UNAM-DGTIC-51 project. JMGH acknowledges the scholarship from UNAM-DGAPA.