Effect of p-GaN hole concentration on the stabilization and performance of a graphene current spreading layer in near-ultraviolet light-emitting diodes

Abstract We have demonstrated the effect of p -GaN hole concentration on a graphene current spreading layer (CSL) for stabilization and improved performance of a near-ultraviolet light-emitting diode (NUV LED). While NUV LEDs with a more lightly-doped p -GaN showed poor electrical and optical properties and unstable performance, NUV LEDs with more heavily-doped p -GaN (∼2 × 10 17  cm −3 ) showed very stable, outstanding performance. The main factor of the improvement was the enhanced contact property between the graphene CSLs and the p -GaN that resulted from the increase of the hole concentration, which led to a thinner barrier and an enhanced current injection. From our results, we were able to determine that hole concentration as heavy as 2 × 10 17  cm −3 in p -GaN layers is a primary condition in NUV LEDs with graphene-based CSLs.