Anisotropic Crystal Structure and High Electron Mobility of Novel Ternary Janus P6XY Monolayers (X/Y = S, Se, Te): First‐Principles Examinations

Abstract Recently, by forming a P‐rich P–S system, the P 3 S monolayer has been predicted to have good resistance to air oxidation, large band gap, high absorption, and superior mobility. Inheriting this prediction, a series of ternary Janus P 6 XY ( X / Y = S, Se, and Te; X ≠ Y ) monolayers based on P 3 X nanosheet are designed and studied. The structures of P 6 XY monolayers are confirmed to be stable based on the evaluation of calculated results for phonon spectra, ab initio molecular dynamic simulations. It is also found that P 6 XY compounds possess anisotropic mechanical characteristics. All Janus structures are indirect semiconductors with large energy gaps varying from 2.12 to 2.60 eV calculated by the hybrid functional. Besides, biaxial strain significantly affects the electronic properties of the P 6 XY monolayers. In particular, the biaxial strains can induce a transition from indirect to direct bandgap in all three P 6 XY structures. The carrier mobility in the three proposed structures exhibits directional anisotropy and high electron mobility value, up to 1.27 × 10 3 cm 2 V −1 s −1 , which are suitable for applications in high‐performance and direction‐dependent nanoelectronic devices.