Numerical study of the suppressed efficiency droop in blue InGaN LEDs with polarization-matched configuration

Abstract

In blue InGaN light-emitting diodes (LEDs), the intuitive approaches to suppress Auger recombination by reducing carrier density, e.g., increasing the number of quantum wells (QWs) and thickening the width of wells, suffer from nonuniform carrier distribution and more severe spatial separation of electron and hole wave functions. To resolve this issue, LED structures with thick InGaN wells and polarization-matched AlGaInN barriers are proposed theoretically. Furthermore, the number of QWs is reduced for the purpose of mitigating the additional compressive strain in AlGaInN barriers. Simulation results reveal that, in the proposed structures, the quantum-confined Stark effect in strained wells is nearly eliminated through the utilization of polarization-matched barriers, which efficiently promotes internal quantum efficiency. Furthermore, the phenomenon of efficiency droop is also markedly improved because of the uniformly distributed or dispersed carriers, and accordingly the suppressed Auger recombination.

InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing the Auger recombination

“…8,9 Moreover, even in the case of the [0001] orientation, the polarization matched condition can be realized by embedding InGaN quantum wells between the properly alloyed quaternary AlGaInN quantum barriers. 10 However, the cost of the nonpolar/semipolar substrates and the limited freedom of epitaxial growth for the quaternary AlGaInN compounds hinder the wide adoption of these solutions. On the other hand, due to the mobility and doping asymmetry for electrons and holes, the electron density is normally higher than the hole density in the quantum wells, and hence the Auger recombination can be effectively reduced if the electrons are evenly distributed in the quantum wells under high current injection level.…”

Luminescence properties of InGaN‐based dual‐wavelength light‐emitting diodes with different quantum‐well arrangements

“…The simulation was carried out using simulation software APSYS , which is capable of dealing with the physical properties of LEDs by solving Poisson's equation, the current continuity equation, the carrier‐transport equation, and Schrödinger equation with proper boundary conditions. This software has been widely used by many groups to study the physical and optical mechanisms of LEDs . In the simulation, the self‐consistent six‐band k · p theory is used to take account of the carrier‐screening effect in the InGaN quantum wells.…”