Polarization-Enhanced p-AlGaN Superlattice Optimization for GUV LED

AlGaN germicidal ultraviolet (GUV) light emitting diodes (LEDs) are one of the most promising disinfection technologies in fighting the COVID-19 pandemic; however, GUV LEDs are still lacking in efficiency due to low p-type doping efficiency in p-AlGaN. The most successful approach for producing conductive p-type AlGaN is the implementation of a polarization-enhanced short period Al $_{\mathbf {x}}$ Ga $_{\mathbf {1-}\mathbf {x}}$ N/Al $_{\mathbf {y}}$ Ga $_{\mathbf {1-}\mathbf {y}}$ N superlattice (SL) structure, which enhances hole injection and reduces device operating voltage. In this report, we investigated different aspects of the superlattice including the Al $_{\mathbf {x}}$ Ga $_{\mathbf {1-}\mathbf {x}}$ N and Al $_{\mathbf {y}}$ Ga $_{\mathbf {1-}\mathbf {y}}$ N alloy constituent compositions, ${x}$ and ${y}$ , period thickness, total thickness, and Mg dopant concentration in terms of LED performance as well as electrical, optical, and morphological characteristics. The polarization-enhanced p-type doping in the AlGaN superlattice was also investigated computationally, giving excellent agreement with experimental results. Highly efficient UVC LEDs (279 nm) with EQE of 2% at 5 A/cm ² were demonstrated. A maximum output power of 5.5 mW (56 mW/mm ² ) was achieved at 100 mA.