Improved Optoelectronic Performance of InGaN/AlGaN Near-Ultraviolet LEDs: Effect of n-GaN Thickness

초록

This study systematically investigates the impact of n-GaN layer thickness on the optoelectronic performance of InGaN/AlGaN-based near-ultraviolet (NUV) light-emitting diodes (LEDs). A comparative analysis is performed between a reference LED and a sample with doubled n-GaN layer thickness. The n-GaN thicknesses considered are 30 and 60 nm beneath the superlattice (SL) layers for reference and thicker n-GaN samples, respectively. Experimental results indicate that increasing the n-GaN thickness significantly improves device performance. Specifically, the thicker n-GaN layer effectively reduces series resistance, piezoelectric field (F-PZ), leakage current, Shockley-Read-Hall (SRH) recombination, and current crowding. The decrease in strain-induced F-PZ improves carrier confinement in the active region, thereby reducing efficiency droop at high injection currents. Furthermore, improved crystal quality in the active region results in reduced SRH recombination and an increased radiative recombination rate, contributing to higher efficiency. Temperature-dependent measurements further reveal that the thicker n-GaN LED exhibits improved thermal stability, with reduced efficiency droop observed even at elevated temperature compared to room temperature. These findings highlight the critical role of n-GaN-layer engineering in optimizing the performance and reliability of NUV-LEDs.

키워드