The effect of employing different carrier gases (H-2 only and 1: 1 vol% N-2: H-2) in the p-type GaN (p-GaN) layer on the wall-plug efficiency (WPE) of high-power light-emitting diodes (LEDs) is studied. Since GaN crystal could be a two-dimension (2-D) growth mode in H-2 ambient, better quality and smoother surface of the p-GaN were obtained. The current spreading performance of the p-GaN layer using H-2 alone as the carrier gas was enhanced, resulting in advanced light output power (LOP). In addition, turn-on voltage and dynamic resistance at 500 mA, which can strongly contribute to the WPE, were also reduced by 0.12 V and 0.13 Omega, respectively. The studied device with H-2 as the carrier gas in the p-GaN layer (p-H-2 layer) exhibits 9.5% and 12.4% improvements in LOP and WPE at 500 mA over the device (N-2/H-2 = 1 : 1), as well as significantly better electrostatic discharge robustness. Therefore, the use of a p-H-2 layer can effectively improve the performance of GaN-basedLEDs for high power applications. (C) 2017 Elsevier Ltd. All rights reserved.