The mesa design guidance based on the effective range of the mesa sidewall reflector towards high-efficiency AlGaN-based DUV LEDs

AlGaN-based DUV LEDs show great application value and are currently confined by LEE. The mesa sidewall reflector is considered as an effective solution in enhancing LEE, but the extra LEE enhancement via reducing mesa size becomes not as significant if the mesa scale is already at low level. The specific mesa scale appropriate for light extraction is determined by effect decay process of the mesa sidewall reflector, which is studied and clarified in this work. By raytracing simulation, the decay length and the effective range of the reflector are estimated to be 20-25 mu m and 40-50 mu m, respectively. Devices with the mesa structures that separate the optical and electrical effects are fabricated, and the results validate the conclusions from the simulations. The mesa design guidance according to the reflector effective range, as well as the LEE enhancement potential of the designed mesa structure, is revealed to achieve high-efficiency DUV LED devices.