Tunable bandgaps, stabilities and optical properties of X3Y (X=C, Si; Y[dbnd]N, P) monolayers with and without strain

Abstract

Our study explores the various properties of a novel class of two-dimensional (2D) monolayer materials, i.e., X3Y (X = C, Si; YN, P). The materials (i.e., C3N, C3P, Si3N, Si3P) exhibit dynamic and thermal stabilities through phonon and molecular dynamics calculations. Under biaxial tensile strain of approximately 11 %, the structures undergo only deformation, indicating their ideal strength. The phonon spectra remain dynamically stable under this 11 % biaxial strain, emphasizing the high mechanical stability of the three materials. The electronic structure showed band gaps of 0.39 eV, 1.56 eV, 0.0 eV, and 0.27 eV for C3N, C3P, Si3N, and Si3P, respectively, which are crucial for electronic devices. Meanwhile, we have found the transitions from metal to semiconductor (Si3N), indirect to direct band gap (Si3P), and semiconductor to metal (C3N, Si3P) by applying compressive and tensile strains to tune the bandgaps. In addition, we have investigated the optical properties excellent absorption in the visible range for C3P, Si3N. Compressive and tensile strains also have a significant effect on these four materials, with both absorption coefficient has been enhanced under strain to some extent. These findings provide potential applications in nano-electronic and opto-electronic devices.