High Anisotropic Optoelectronics and Robust Transport Performance in Two-Dimensional Single-Layer and Bilayer As4P6

Two-dimensional black arsenic phosphorus has attracted significant interest due to its extraordinary electronic, optical, and transport properties. Therefore, in this work, we go through all the possibilities, including 3297 nonrepetitive configurations, and demonstrate the lowest energy structure of the As_xP_1–x (x = 0.4) monolayer by first-principles calculations. Our results indicate that both single-layer and bilayer As₄P₆ host direct and indirect bandgap semiconductors with bandgaps of 1.94 and 1.26 eV, respectively, which exhibit good light adsorption within the visible light and infrared region. Moreover, both single-layer and bilayer As₄P₆ possess high electron and hole mobilities (up to 2.6 × 10⁴ cm² v^–1 s^–1), which also exhibit extreme carrier anisotropy originating from their high in-plane lattice anisotropy. Furthermore, bilayer As₄P₆ exhibits exceptional device characteristics including a lower threshold voltage, higher on-state current, and higher conductance. In addition, the transmission coefficient spectrum of bilayer As₄P₆ is three times greater than that of the monolayer owing to an increased number of electronic channels. Additionally, the extinction ratio of single-layer As₄P₆ exhibits high anisotropy, indicating enhanced polarization sensitivity in the zigzag direction. Our findings provide two excellent candidate materials for the application of optoelectronic devices.