Radiative Recombination Enhancement of Single-Contact Micro-LEDs Driven by AC Power via Varying Pairs of Multiple Quantum Wells

Gallium nitride-based nano/microscale light-emitting diodes operating under alternating-current single-contact driving have garnered significant attention due to their unique device characteristics and potential applications in device-level encryption, mimicking biological afferent nerves and self-emissive displays. In this work, we investigate the influence of quantum well periods on the performance of single-contact GaN blue micro-LEDs under AC driving, where the anode is directly formed on the p-type GaN and the cathode is formed on the backside of the sapphire substrate. Under AC driving, devices with fewer quantum well periods exhibit higher peak currents and stronger electroluminescence. In particular, the device with three quantum wells shows a reduced working voltage of 16.3 V, which is 29.4% lower than that of the device with nine quantum wells. These results demonstrate single-contact micro-LEDs with fewer quantum well pairs had higher efficiencies under AC driving. Finite-element modeling further shows that reducing the number of quantum well periods increases the hole concentration within the wells during the forward half-cycle of AC driving, a consequence of the larger equivalent capacitance that strengthens current injection under AC excitation.