Enhanced efficiency of deep ultraviolet light-emitting diodes utilizing full-coverage Al reflector and highly reflective Ni/Rh p-electrode

Abstract Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.