Observation of robust anisotropy in WS2/BP heterostructures

Two-dimensional (2D) anisotropic materials have garnered significant attention in the realm of anisotropic optoelectronic devices due to their remarkable electrical, optical, thermal, and mechanical properties. While extensive research has delved into the optical and electrical characteristics of these materials, there remains a need for further exploration to identify novel materials and structures capable of fulfilling device requirements under various conditions. Here, we employ heterojunction interface engineering with black phosphorus (BP) to disrupt the C3 rotational symmetry of monolayer WS2. The resulting WS2/BP heterostructure exhibits pronounced anisotropy in exciton emissions, with a measured anisotropic ratio of 1.84 for neutral excitons. Through a comprehensive analysis of magnetic-field-dependent and temperature-evolution photoluminescence spectra, we discern varying trends in the polarization ratio, notably observing a substantial anisotropy ratio of 1.94 at a temperature of 1.6 K and a magnetic field of 9 T. This dynamic behavior is attributed to the susceptibility of the WS2/BP heterostructure interface strain to fluctuations in magnetic fields and temperatures. These findings provide valuable insights into the design of anisotropic optoelectronic devices capable of adaptation to a range of magnetic fields and temperatures, thereby advancing the frontier of material-driven device engineering.