Carrier Dynamics and Structural Analyses of Orange/Red In-Rich InGaN Double-Quantum Wells LED Hybridized by Blue InGaN Single-Quantum Well.

The carrier dynamics of orange/red LEDs incorporating In-rich InGaN/GaN double quantum well (DQW) structures are explored. The improved hybrid LED structure incorporates an In-poor InGaN single quantum well (SQW) alongside DQWs that are characterized by enhanced efficiency compared to the control LED comprises InGaN/GaN DQWs solely. Advanced structural characterizations reveal a unique periodic V-shaped accumulation of Al around threading dislocations (TDs) in the n-AlGaN layer, providing insights into strain distribution around TDs. Advanced optical analyses unveil distinct carrier dynamics. Temperature- photoluminescence (PL), and time-resolved PL reveal unusual behavior in In-rich InGaN LEDs. Unlike blue In-poor InGaN-based LED, the In-rich orange/red LED exhibited a sharp, step-like energy shift accompanied by an abrupt change in the peak width within the intermediate temperature (160-200 K) range. Cathodoluminescence reveals that, in Hybrid LED, the orange/red emission is consistent around V-pits/trenches, while a significant DQW damage occurs below these defects in Control LED, where AlInGaN is formed, resulting in blue emission. Reduced quantum-confined Stark effect is observed in Hybrid LED, addressing key challenges in long-wavelength nitride emitters. The blue SQW inclusion effectively suppresses non-radiative recombination and serves as an efficient carrier reservoir for the active region, achieving a remarkable internal quantum efficiency (27.9%) for the Hybrid LED.