Nature Reviews Physics | 2019
Black phosphorus and its isoelectronic materials
Abstract
The family of 2D and layered materials has been expanding rapidly for more than a decade. Within this large family of hundreds of materials, black phosphorus and its isoelectronic group IV monochalcogenides have a unique place. These puckered materials have distinctive crystalline symmetries and exhibit various exciting properties, such as high carrier mobility, strong infrared responsivity, widely tunable bandgap, in-plane anisotropy and spontaneous electric polarization. Here, we review their basic properties, highlight new electronic and photonic device concepts and novel physical phenomena and discuss future directions.Layered black phosphorus and its isoelectronic group IV monochalcogenides have distinctive physical properties arising from their unusual crystal symmetries. This Review discusses some of the interesting physical phenomena, possible device applications and future research directions for this group of materials.Key pointsThe crystalline symmetries of layered black phosphorus and its isoelectronic group IV monochalcogenides play a very important role in the determination of their physical properties.Black phosphorus is likely to be the layered semiconductor material with the highest carrier mobility at room temperature, making it promising for high-performance electronic applications.Black phosphorus, arsenic phosphorus and other group V alloys may find applications in mid-infrared photonics as alternative material systems owing to their layered nature and moderate bandgap.Monolayer group IV monochalcogenides have a broken inversion symmetry and spontaneous in-plane electric polarization. They present a great platform for the exploration of piezoelectricity, ferroelectricity, ferroelasticity and multiferroics.In black phosphorus and other group V alloys, the interplay between the crystal symmetry and spin–orbit coupling may lead to the realization of rich topological states.Wafer-scale synthesis of this group of materials remains challenging. Future research may leverage the phase transition induced by pressure, temperature or high-intensity light.