First-principles study of two-dimensional MoP2Si2Z2 (Z=N, P, As) monolayer

Abstract

Two-dimensional MoP2Si2Z2 (Z = N, P, As) monolayers were designed and studied by first-principles calculations. The layers are semiconductors, of which the MoP2Si2N2 and MoP2Si2P2 monolayers have a direct bandgap of 0.014 (0.522) and 0.673 (1.151) eV, respectively, at PBE (HSE06) level. The MoP2Si2As2 monolayer has almost the same indirect and direct band gaps (0.509/0.903 eV at the PBE/HSE06 level). The calculated optical absorptions (less than 2 × 104 cm−1 in the visible region) show that the MoP2Si2P2 and MoP2Si2As2 monolayers are well transparent materials, while the MoP2Si2N2 monolayer has an absorption peak in the infrared region. The layers have good mechanical properties and high carrier mobility. The Young's moduli (E2D) are 314, 206 and 187 N m−1 for MoP2Si2N2, MoP2Si2P2 and MoP2Si2As2 respectively. The carrier mobility of MoP2Si2N2 in zigzag direction (μzig) reaches 2855.3 (electron) and 1280.2 (hole) cm2V−1s−1, respectively. Transitions between metal and semiconductor, and between direct and indirect semiconductors, can be realized for monolayers by in-plane biaxial strain. The properties resulting from the first-principles calculation motivate to synthetize of these monolayers and use them in microelectronics.