Oxygenation of Janus group III monochalcogenides: First-principles insights into GaInXO ( X=S , Se, Te) monolayers

In this paper, we design and predict the structural, electronic, transport, and optical properties of two-dimensional Janus $\mathrm{GaIn}X\mathrm{O}$ ($X=\mathrm{S}$, Se, Te) monolayers by using first-principles calculations. The stability of all six possible configurations of $\mathrm{GaIn}X\mathrm{O}$ was examined through the analysis of their phonon spectra. It is found that, except for the OGaInTe monolayer, all the other configurations are dynamically stable. Further, the mechanical stability has been also investigated via calculations for the elastic constants. Depending on the stacking configuration, $\mathrm{GaIn}X\mathrm{O}$ can be either semiconductor (with a direct or indirect band gap) or metallic. Interestingly, the carrier mobilities of the investigated systems are found to be highly directional isotropic; however, the mobility of electrons is much higher than that of holes, suggesting that these monolayers can be potential materials for applications in nanoscale electronics. Finally, strong optical absorption in a wide light region extending from the infrared to the ultraviolet region is also predicted in the Janus $\mathrm{GaIn}X\mathrm{O}$ depending on its stacking configuration. The findings not only get insights into the fundamental properties of the Janus materials based on group III monochalcogenide monolayers but also suggest them as potential candidates for applications in the next-generation optoelectronic nanodevices.