Theory of second-order piezoelectric fields in III-N nanostructures

We present a detailed analysis of second-order piezoelectric fields in wurtzite nitride nanostructures. A symmetry adapted approach is used to describe these fields as a function of the growth plane. The derived analytic expression can easily be implemented in existing codes for quantum dots and wells. In terms of the field strength, our results reveal that when including second-order effects an improved agreement between theory and experiment is achieved. Our calculations indicate that in nonpolar InGaN/GaN dots, second-order effects can further reduce residual first-order related fields. In c-plane systems, second-order effects become significant with increasing In content.