First-principles study of the structures and fundamental electronic properties of two-dimensional P0.5As0.5 alloy

In this work, the structures, stabilities and electronic properties of 25 possible two-dimensional (2D) binary P0.5As0.5 alloys were systematically investigated. We found that - and -phase are the two most favourable lattice configurations for atomic positional fluctuation. Moreover, we show that the predicted structure IV is slightly more stable than the previously proposed structure III for elementary distribution. Our results indicate that atomic positional fluctuation and elementary distribution are two effective routes to modulating the electronic properties of the 2D P0.5As0.5 alloy with direct or indirect band-gaps.