Potential outstanding physical properties of novel black arsenic phosphorus As_0.25P_0.75/As_0.75P_0.25 phases: a...

Black arsenic phosphorus As_0.5P_0.5 has been studied as an excellent candidate for electronic and optoelectronic applications. At the same time, the physical properties of As P_1- alloys with other compositions were not investigated. In this work, we design seven As_0.25P_0.75(P-I and P-II)/As_0.75P_0.25(As-(I, II, III, IV and V)) phases with molecular dynamics stability. First principles calculations are used to study their electronic structures under strain as well as their carrier mobilities. By calculating Perdew-Burke-Ernzerhof (PBE) electronic bands, we reveal that these materials are direct-gap semiconductors similar to black phosphorus except for the As-IV phase. It is also found that the carrier mobility in the P-I and As-V phases can reach 10⁴ cm² V^-1 s^-1. The electronic structures of the P-I, As-IV and As-V phases under strain are studied. Finally, we design caloritronic devices based on armchair and zigzag nanoribbons. The value of the Seebeck coefficient of the armchair and zigzag devices made from the P-II phases are found to be as high as 2507 and 2005 μW K^-1 at 300 K. The thermal properties of the arsenic phosphorus phases under consideration are further studied by calculating their thermoelectric figure of merit, ZT values. These values are as high as 10.88 for the armchair devices based on the As-III phase and 4.59 for the zigzag devices based on the As-V phase at room temperature, and 15 and 7.16 at 600 K, respectively. The obtained results demonstrate that the As_0.25P_0.75/As_0.75P_0.25 phases studied here can be regarded as potential candidates for thermoelectric and electronic device applications.