Intrinsic and engineered properties of black phosphorus

Black phosphorus (BP) is a two-dimensional (2D) layered semiconductor with tunable direct bandgap, high carrier mobility, balanced on/off ratio and significant crystal anisotropy. These properties provide unrivalled advantages for its applications in electronic and optoelectronic devices. To fulfill its potential, much research has conducted to exploring the intrinsic properties of BP and developing strategies to engineer desirable properties. In this review article, the state-of-the-art knowledge of intrinsic and engineered properties of BP is examined, and the existing results are discussed in depth. Particular focus is placed on the electrical, optical, thermal, and mechanical properties of BP, and highlights the evolution behaviors of these properties with the crystal orien-tation, thickness and temperature. Then, strategies for tuning these properties by tailoring the strain, electric field, and doping conditions are reviewed, along with a detailed discussion of the relevant mechanisms. The final part of this paper provides insights into the challenges and opportunities associated with the research and development on BP with novel and interesting properties.