Correct implementation of polarization constants in wurtzite materials and impact on III-nitrides

TL;DR

This paper clarifies the correct calculation of polarization constants in wurtzite materials, emphasizing the importance of proper references and constants for accurate electronic property predictions in III-nitrides.

Contribution

It introduces a consistent method for determining polarization discontinuities in III-nitride materials using appropriate references and piezoelectric constants.

Findings

Corrected polarization discontinuity values for GaN, AlN, and InN

Highlighting the impact of reference choice on polarization calculations

Comparison with experimental data supports the proposed method

Abstract

Accurate values for polarization discontinuities between pyroelectric materials are critical for understanding and designing the electronic properties of heterostructures. For wurtzite materials, the zincblende structure has been used in the literature as a reference to determine the effective spontaneous polarization constants. We show that, because the zincblende structure has a nonzero formal polarization, this method results in a spurious contribution to the spontaneous polarization differences between materials. In addition, we address the correct choice of "improper" versus "proper" piezoelectric constants. For the technologically important III-nitride materials GaN, AlN, and InN, we determine polarization discontinuities using a consistent reference based on the layered hexagonal structure and the correct choice of piezoelectric constants, and discuss the results in light of available experimental data.