III-Nitride multiple disk-in-wire laser structures: Effects of crystal orientation and spacer size

Atomistic numerical simulations have been carried out to study the performance of recently reported optical structures based on nonpolar multiple disk-in-wire In0.08Ga0.92 N/GaN material system. The simulations are performed with an augmented version of the open-source NEMO 3-D software that uses a fully-atomistic valence force-field (VFF) for strain distributions and empirical sp3s*-spin tight-binding model to compute the electronic structure. Both linear and nonlinear components of internal polarization field have been included using a recently proposed first-principles based polarization model. When compared to conventional c-plane based polar structures, the nonpolar device exhibits a much weaker (yet non-zero) internal potential and improved laser emission characteristics. In particular, it is found that the optical transition probability is a strong function of the internal fields and could be tuned via engineering the spacer size.