Enhancement of Light Extraction Efficiency in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes Using Cooperative Scattering Structures on the n-AlGaN Layer

Abstract

The efficiency of AlGaN based deep ultraviolet light-emitting diode (DUV LEDs) are mainly hindered by the light extraction issue. In this work, an innovative cooperative scattering structure is introduced that combines a nanopore configuration with an aluminum (Al) nanoparticle array on the n-AlGaN layer of the DUV LEDs. The integration of these two scattering arrays can enhance light extraction by mitigating total internal reflection at the device interface. The nanopores are formed on the n-AlGaN surface by electrochemical etching and optimized by varying the etching voltage, while the Al particles are formed by thermal annealing. With the help of the cooperative scattering structure, the light output power (LOP) of the optimized DUV LEDs is significantly increased by 77.6% and a notable 2.2 times is achieved in its light extraction efficiency (LEE) enhancement factor. Moreover, Finite-Difference Time-Domain (FDTD) simulations have validated that the cooperative scattering structure considerably enhances the LEE for both Transverse Electric (TE) and Transverse Magnetic (TM) modes, respectively. This work paves the way to fabricate high efficiency DUV LEDs via novel scattering structure designs.