Deep Ultraviolet Light Source from Ultrathin GaN/AlN MQW Structures with Output Power Over 2 Watt
High‐output‐power electron‐beam (e‐beam) pumped deep ultraviolet (DUV) light sources, operating at 230–270 nm, are achieved by adjusting the well thickness of binary ultrathin GaN/AlN multiple quantum wells. These structures are fabricated on high‐quality thermally annealed AlN templates by metal‐organic chemical vapor deposition. Owing to the reduced dislocation density, large electron–hole overlap, and efficient carrier injection by e‐beam, the DUV light sources demonstrate high output powers of 24.8, 122.5, and 178.8 mW at central wavelengths of 232, 244, and 267 nm, respectively. Further growth optimization and employing an e‐gun with increased beam current lead to a record output power of ≈2.2 W at emission wavelength of ≈260 nm, the key wavelength for water sterilization. This work manifests the practical levels of high‐output‐power DUV light sources operated by using e‐beam pumping method.