Nonlinear Polarization and Efficiency Droop in Hexagonal InGaN/GaN Disk-in-Wire LEDs

TL;DR

This study investigates how nonlinear piezoelectric effects influence electronic states and efficiency droop in hexagonal InGaN/GaN disk-in-wire LEDs, combining atomistic modeling with device simulations.

Contribution

It applies a first-principles-based nonlinear piezoelectric model within an atomistic framework to analyze its impact on LED performance.

Findings

Nonlinear piezoelectricity significantly affects electronic states.

Atomicity and polarization fields influence quantum efficiency.

Efficiency droop is linked to nonlinear polarization effects.

Abstract

Recent studies suggest that piezoelectric polarization can play an important role in determining the electronic and optical properties of nanoscale nitride heterostructures. Among a few models available, recent first-principles calculations performed by Prodhomme et al. provide a simple yet accurate description of linear and nonlinear piezoelectric coefficients in reduced dimensionality structures having wurtzite crystal symmetry. In this paper, first, within a fully atomistic VFF-sp3s* tight-binding framework, we employ the model proposed by Prodhomme et al. to evaluate the importance of nonlinear piezoelectricity on the single-particle electronic states and interband optical transitions in a recently reported hexagon shaped In0.25Ga0.75N/GaN disk-in-wire LED. The microscopically determined transition parameters are then incorporated into a TCAD toolkit to investigate how atomicity and the net polarization field affect the internal quantum efficiency of the LED and lead to a degraded efficiency droop characteristic