Low-droop and high-efficiency (>40%) UVA emitters enabled by precursor modulated quantum wells

We demonstrate a precursor-modulation growth scheme to overcome the efficiency limitations of ultraviolet-A (UVA) light emitting diodes (LEDs) caused by interface intermixing and poor carrier confinement. By incorporating intentional growth interruptions, we engineered more abrupt interfaces with Al-rich interfacial “spikes.” Scanning transmission electron microscopy energy-dispersive x-ray spectroscopy mapping and Schrödinger–Poisson simulations confirm these spikes increase conduction- and valence-band offsets by over 50%, improving electron–hole wavefunction overlap by approximately 20%. The resulting 380-nm micro-LEDs achieved a peak external quantum efficiency of 41%. Notably, the devices maintain high efficiency above 40% up to a current density of 200 A/cm2 with negligible droop. This approach provides a scalable and robust pathway for high-power, high-efficiency solid-state UVA emitters.