Metalorganic chemical vapor deposition grown n-InGaN/n-GaN tunnel junctions for micro-light-emitting diodes with very low forward voltage

High performance GaN-based micro-light-emitting diodes (mu LEDs) with epitaxial n-InGaN/n-GaN tunnel junctions (InGaN TJs) were grown by metalorganic chemical vapor deposition (MOCVD). The InGaN TJs mu LEDs show a significant reduction of forward voltage (V-f) by similar to 0.6 V compared to the common TJs mu LEDs. The V-f at 20 A cm(-2) is very low varied from 3.15 V to 3.19 V in small InGaN TJ mu LEDs with a size less than 40 x 40 mu m(2), and then significantly increases in large LEDs. Selective area growth (SAG) of TJs can overcome such size limitation by vertical out diffusion of hydrogen through the apertures on top of p-GaN. The InGaN TJ mu LEDs overgrown by SAG show a size-independent low V-f ranged from 3.08 V to 3.25 V. The external quantum efficiency (EQE) of the packaged TJ mu LEDs was improved by 6% compared to the common mu LEDs with indium tin oxide (ITO) contact. This work solves the key challenges of MOCVD-grown TJs.