The tunable bandgap of phosphorus-arsenic alloys for mid-and long-infrared regime photodetectors

Abstract

Alloys are an effective and practical synthetic strategy for modulating the bandgap of materials. Here, we construct a series of phosphorus-arsenic alloys, hoping to effectively tune the bandgap width by introducing arsenic elements in the phosphorus monolayer. Among the many isomers, we have chosen the most stable α and β phases to construct the alloys. For the α phase, the introduction of arsenic can effectively narrow the bandgap width (0.92–0.15 eV), while for the β phase, the introduction of arsenic does not drastically change the bandgap width (1.63–0.99 eV) than that of α phase, and this difference in electronic structure largely arises from the anisotropy of the structure itself and its tolerance to strain. The design of this alloy is promising for the application of this material in photodetectors in the mid- and long-infrared wavelengths.