Investigation of the microscopic mechanisms for InGaN quantum well performance optimization in UVA-LEDs

Abstract

InGaN multiple quantum wells (MQWs) operating in the ultraviolet A spectral band face significant challenges in achieving high quantum efficiency due to the pronounced quantum-confined Stark effect (QCSE) and the difficulty of incorporating In at low In compositions. This work employs a dual strategy of optimizing ultra-thin QW structures and incorporating GaN interlayers to enhance the quantum efficiency of InGaN/GaN heterostructures. The synergistic interplay between the quantum confinement effect and interfacial strain effectively reduces the density of non-radiative recombination centers and mitigates the detrimental impact of the QCSE. Combining electron energy loss spectroscopy with first-principles calculations, we have characterized the local charge reconstruction at the heterointerfaces. This characterization unequivocally confirms the regulatory role of QW interfaces with different thicknesses in modulating the built-in electric field. Our findings provide a novel research paradigm for a more in-depth exploration of the mechanisms governing interface and defect behavior in semiconductor heterostructures.