The Correlation between Surface V-Shaped Defects and Local Breakdown Phenomena in GaN-Based LEDs

Abstract

This paper investigates the intriguing impact of surface V-shaped defects on the electrical and optical characteristics of GaN-based LEDs, particularly under reverse bias conditions. These defects introduce unique luminescence phenomena, notably giant dot-like luminescence (GDL), and exert significant influence on device performance. The size of these V-shaped defects plays a critical role: larger defects generate more indium-rich regions at their base, resulting in elevated tensile stress. This heightened stress promotes carrier tunneling, increasing reverse leakage current and leads to GDL formation. However, even with multiple V-shaped defects present, localized failure predominantly occurs at the defect experiencing the highest tensile stress, substantially reducing the breakdown voltage. Micro-Raman analysis further reveals distinct Raman shifts and increased tensile stress in these regions. These findings underscore the complexity of V-shaped defects’ effects, highlighting their importance in GaN-based LED design and optimization. Recognizing their influence on electrical and optical properties can significantly impact device reliability and performance, particularly in reverse bias conditions.