Black Arsenic-Phosphorus: Layered Anisotropic Infrared Semiconductors with Highly Tunable Compositions and Properties

摘要

Two-dimensional (2D) layered materials with diverse properties have attractedsignificant interest in the past decade. The layered materials discovered sofar have covered a wide, yet discontinuous electromagnetic spectral range fromsemimetallic graphene, insulating boron nitride, to semiconductors withbandgaps from middle infrared to visible light. Here, we introduce new layeredsemiconductors, black arsenic-phosphorus (b-AsP), with highly tunable chemicalcompositions and electronic and optical properties. Transport and infraredabsorption studies demonstrate the semiconducting nature of b-AsP with tunablebandgaps, ranging from 0.3 to 0.15 eV. These bandgaps fall into long-wavelengthinfrared (LWIR) regime and cannot be readily reached by other layeredmaterials. Moreover, polarization-resolved infrared absorption and Ramanstudies reveal in-plane anisotropic properties of b-AsP. This family of layeredb-AsP materials extend the electromagnetic spectra covered by 2D layeredmaterials to the LWIR regime, and may find unique applications for future all2D layered material based devices.