Enhancing the Yellow-LED Performance with Improvised Pre-Stress Alleviation layer: A Theoretical and Numerical Analysis

Abstract The decline in quantum efficiency observed in yellow-LEDs emitting wavelength around ~575 nm, commonly known as the “green-yellow gap”, is predominantly influenced by the fact that high In-content InxGa1−xN/GaN (x =30%) yellow-multiple quantum wells (yellow-MQWs) are typically grown on GaN template. This configuration leads to substantial compressive stress, contributing to the structural defects and the significant quantum confined stark effect. To address this challenge, our strategy involves achieving superior lattice constant alignment within the yellow-MQWs by growing a pre-stress alleviation layer (PSAL) prior to the growth of yellow-MQWs. Our comprehensive theoretical study, coupled with numerical simulations, aimed to explore the impact of two distinct practical and commercially viable PSAL approaches: pre-quantum well, comprising short periods of InYGa1−YN/GaN and pre-thin layer, incorporating a thin layer of InZGa1−ZN. Following a thorough analysis of these approaches, we propose an innovative improved optimized structure that demonstrates the highest internal quantum efficiency of 74.2 %, minimal efficiency droop of 14.7% at 20 A/cm2, and a 20 nm favourable red-shift in electroluminescence characteristic with narrower full-width-half-maximum of 28 nm without any adverse effect on the pure yellow-color emission at 20 A/cm2. This advancement holds promise for providing better crystal quality and addressing the green-yellow gap issue in yellow-LED technology.