10.4% external quantum efficiency 294 nm UV LEDs at 20 A/cm² with a fully transparent tunnel junction

We report on the successful demonstration of an all metalorganic chemical vapor deposition (MOCVD) grown fully transparent tunnel junction (TJ) germicidal UV LED, resulting from the use of a lightly doped n^--AlGaN contact layer enabling rapid MOCVD growth optimization. We found that the optimal condition for LED performance was a 3 nm p⁺⁺-Al_0.6Ga_0.4N / 9 nm n⁺⁺-Al_0.65Ga_0.35N TJ above a 20 period 1 nm p-Al_0.8Ga_0.2N/ 1 nm p-Al_0.2Ga_0.8N short-period superlattice (SPSL). We observed a peak external quantum efficiency (EQE) of the λ = 294 nm TJ UV LED of 12.1%, and an EQE of 10.4% at 20 A/cm² and 9.1% at 35 A/cm², with an excess voltage of 1.5 V at 1 A/cm².