Structural and Electronic Properties of Two-Dimensional Janus XGeSiY (X, Y = P, As, Sb, and Bi) Monolayers: A First-Principles Study

Herein, the dynamical stability and electronic, optical, and transport properties of Janus two-dimensional (2D) XGeSiY (X and Y = P, As, Sb, and Bi) monolayers are investigated based on first-principles calculations. The stability of 16 Janus configurations of XGeSiY monolayers, except the BiGeSiP monolayer, is validated via the study on cohesion energies and phonon spectra. Based on varying structural stacking configurations, XGeSiY monolayers can exhibit a direct or indirect bandgap. Janus XGeSiY monolayers can exhibit significant optical absorption with a broad spectrum ranging from infrared to ultraviolet regions. The carrier mobilities of the studied systems are highly anisotropic. In stable Janus XGeSiY monolayers, the mobility of electrons is considerably higher than that of holes. These results imply that Janus XGeSiY monolayers can be considered as potential applied electronic materials for next-generation optoelectronics.