Demonstration of Full AlGaN Tunnel Junction Ultraviolet LED

In this study, we have demonstrated the full AlGaN tunnel junction (TJ) ultraviolet light-emitting diode (UV LED). The TJ UV LED was grown on SiC substrates by metal–organic vapor phase epitaxy. The growth started with the n-Al0.3Ga0.7N cladding layer and then the TJ comprising a graded n-AlGaN layer, a thin undoped Al0.8Ga0.2N interlayer, and a graded p-AlGaN layer. Subsequently, the Al0.2Ga0.8N/Al0.45Ga0.55N quantum well active region and the topmost n-Al0.3Ga0.7N were grown. I–V measurements revealed that the device resistance and turn-on voltage of the TJ UV LED were significantly reduced compared with the reference UV LED, owing to enhanced hole injection and improved contact between the metal and topmost AlGaN. Electroluminescence measurements showed that the emission intensity of the TJ UV LED was enhanced by ∼2 times compared with the reference UV LED. This work demonstrates that full AlGaN TJ can be realized and is promising for high-performance light-emitting devices operating in the UV region.