In this paper, the structural, electronic and optical properties of tetragonal binary monolayers of MX (M = Sc, Y; X = As, Bi, N, P, Sb) are investigated using the density functional theory. The optical study demonstrates that ScN and YN compounds are promising anti-reflective materials. All compounds are found to be semiconductors with a bandgap in the range of 0.45–1.8 eV. Among these compounds, ScN and YN have a direct bandgap at Γ-point while the remainings demonstrate an indirect bandgap. It is found that the structural anisotropy controls the anisotropy of the electronic properties. The biaxial strain analysis shows that YBi monolayer has the maximum linear strain bandgap dependency, making it a suitable candidate for pressure sensing applications. The ScN and YN monolayers demonstrate a phase transition from semiconductive to Dirac semi-metallic characteristics at large compressive strains.
