  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
