Effect of V-Pits Coverage Optoelectronic Characteristics in Green GaN-Based Mini-Light-Emitting Diodes Grown by MOCVD

Abstract

V-pits have been intensively studied for their role in light-emitting diodes (LEDs). The coverage of V-pits in InGaN/GaN multi-quantum wells (MQWs) is critical for suppressing leakage path through electron blocking layer (EBL). In this study, we have investigated the coverage of V-pits in green mini-LEDs modulated via growth parameters optimization and systematically analyzed the characteristics of the photoelectric properties associated with V-pits coverage on device. Elevated temperatures and pressures result in enhanced adatoms migration, which can achieve a coverage up to 98.8% of V-pits, improving the crystal quality due to stable surface. Electrical characterization reveals that although high-coverage devices exhibit suppressed leakage current, their peak external quantum efficiency (EQE) decreases, more seriously spectral blue shift and operating voltage increase due to compromised hole transport uniformity. Intriguingly, intermediate-coverage samples demonstrate superior breakdown voltage characteristics. Current–voltage curve analysis shows the ideality factor increases from 1.8 to 2.5 with improved coverage, indicating aggravated Shockley–Read–Hall (SRH) recombination with covered V-pits.