Nonlinear polarization and efficiency droop in hexagonal InGaN/GaN disk-in-wire LEDs

In this paper, we computationally evaluate the influence of nonlinear piezoelectricity in a recently reported hexagon shaped In0.25Ga0.75N/GaN disk-in-wire light emitting diode (LED). To calculate the single-particle electronic states and the interband optical transition rates, we have employed a fully atomistic valence force field (VFF)-sp(3)s* tight-binding framework coupled with a recently proposed (first-principles based) polarization model from Prodhomme et al. (2013). The microscopically determined transition parameters are then incorporated into an LED simulator to investigate how atomicity, strain relaxation, and the net polarization field affect the internal quantum efficiency and lead to a degraded droop characteristic. (C) 2015 Elsevier Ltd. All rights reserved.