Ultraviolet Light-Emitting Diode Using Nonpolar AlGaN Core-Shell Nanowire Heterostructures

Highly efficient nonpolar AlGaN nanowire ultraviolet light-emitting diode is developed, wherein core-shell AlGaN multiple quantum well layers are incorporated in the nonpolar active regions. It is confirmed that the core-shell light-emitting diode (LED) heterostructures are uniformly grown on the nonpolar surfaces of hexagonal GaN nanowires by metalorganic chemical vapor deposition (MOCVD) technique. At room temperature, the nearly defect-free core-shell AlGaN nanowire heterostructure exhibits high luminescence efficiency (approximate to 74%) in the ultraviolet (UV) wavelength. Compared to conventional uniaxial AlGaN nanowire LED structure, the external quantum efficiency is significantly improved due to dramatically reduced dislocation density and suppressed polarization field, as well as improved carrier injection efficiency. Moreover, the absence of quantum-confined Stark effect is clearly observed by power-dependent cathodoluminescence and electroluminescence measurements. This study provides a viable path to realize high-power UV LEDs, which is critically important for a broad range of applications, including sterilization, disinfection, sensing, and medical diagnostics.