Electrically injected InGaN/GaN micro-light emitting diodes: Size-dependent diode characteristics and recombination dynamics

Abstract

This work demonstrates InGaN/GaN multiple quantum well micro-light emitting diodes (μLEDs) grown on c-plane sapphire substrates via metalorganic chemical vapor deposition, focusing on size-dependent efficiency, leakage, and temperature-dependent performance. Micro-LEDs with radii of 1–50 μm were fabricated using nanofabrication techniques. Current–voltage characteristics, modeled with a two-diode approach, reveal size-dependent peripheral leakage decreasing with radius, with ideality factors indicating near-ideal behavior for larger devices. Electroluminescence measurements show high slope efficiency for smaller radii at low bias, with early compression in 1–2.5 μm devices due to high carrier density. The ABC recombination model quantifies Shockley–Read–Hall, radiative, and Auger processes, showing size-dependent non-radiative contributions. Electroluminescence spectra exhibit blueshift with bias, attributed to quantum-confined Stark effect (QCSE) screening, pronounced in smaller devices. Temperature-dependent electroluminescence displays non-monotonic intensity, balancing radiative efficiency gains against hole freeze out in p-GaN. These findings highlight the interplay of QCSE, leakage, and carrier dynamics, advancing efficient μLEDs.