Polarization-matching and carrier confinement in III-nitride deep-ultraviolet light-emitting diodes

Abstract

The polarization-induced quantum confined Stark effect has been recognized as a significant factor contributing to the Internal Quantum Efficiency (IQE) droop in light-emitting diodes (LEDs). This study focuses on the design of LEDs by investigating the InAlN/AlGaN interface. By incorporating InAlN quantum wells, a polarization-matched (PM) multi-quantum well (MQW) LED architecture was developed. While the flat conduction and valence bands on PM MQWs indicate an improved recombination rate, it is crucial to examine the impact on IQE, considering carrier confinement and injection efficiency influenced by the band offsets. This paper presents a numerical analysis comparing two LEDs emitting at 245 and 275 nm, respectively. The results demonstrate that the PM LED operating at 275 nm exhibits enhanced performance, benefiting from high probability density overlap. Conversely, the PM LED emitting at 245 nm demonstrates poor confinement, resulting in an overall low performance, regardless of polarization matching.

Optical Gain in AlGaN Quantum Wells: Impact of Higher Energy States

“…However, part of these interface charges can be screened by electrons and holes from trap states and external charges [20], which originate from outside the simulated region. In lieu of a full device transport simulation, we model this as a reduction of the effective polarization charge by a factor p eff which depends on operation mode (electrical [21]- [23] vs. optical pumping [20], [24]).…”