Evidence for nonlinear macroscopic polarization in III–V nitride alloy heterostructures

We provide explicit rules to calculate the nonlinear polarization for nitride alloys of arbitrary composition, and hence, the bound sheet charge induced by polarization discontinuity at the interfaces between different alloy and binary (epi)layers. We then present experimental results and simulations of polarization-related quantities in selected nitride-alloy-based heterostructure systems. The agreement of experiment and simulation, also in comparison to previous approaches, strongly suggests that the macroscopic polarization of nitride alloys is indeed nonlinear as a function of composition.