Polarization Sensitive Vacuum‐Ultraviolet Photodetectors Based on m‐Plane h‐BN

Abstract Vacuum ultraviolet (VUV) detection plays an essential role in space science, radiation monitoring, electronic industry, and fundamental research. Integrating polarization characteristics into VUV detection enriches the comprehension of the target attributes and broadens the signal dimensionality. Polarization detection has been widely developed in visible and infrared regions; however, it is still relatively unexplored in VUV light due to the lack of photoactive materials with low‐symmetry structures, VUV selective response and radiation resistance. Here, the wafer‐scale hexagonal boron nitride (h‐BN) epitaxial films with the distinct m ‐plane surfaces are demonstrated that exhibit significant anisotropy due to space symmetry breaking, instead of the routinely obtained high‐symmetry c ‐planes governed by the most thermodynamically stable growth mode. This results in notable anisotropy in light absorption and charge density distributions, yielding a dichroic ratio greater than 10 and a carrier transport efficiency ratio ( μτ a ‐axis / μτ c ‐axis ) of 24. The h‐BN based detector achieves a high polarization ratio of 6.2 for 188 nm VUV polarized light, reaching the short‐wavelength limit of the reported polarization‐sensitive photodetectors. This work presents an effective strategy for designing polarized VUV photodetector from h‐BN, and paves the road towards the novel integrated optoelectronics, photonics and electronics based on traditional 2D materials.