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Quantification of polarization bowing in III-nitrides by off-axis electron holography and impact on the polarization controversy

Qianqian Lan1,*, Michael Schnedler1, Keyan Ji1, Jean-François Carlin2, Raphaël Butté2, Nicolas Grandjean2, Rafal E. Dunin-Borkowski1, and Philipp Ebert1

  • *Contact author: q.lan@fz-juelich.de
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Phys. Rev. B 113, 155302 – Published 3 April, 2026

DOI: https://doi.org/10.1103/4rsc-ysk8

Abstract

Polarization engineering has played an important role in advancing III-nitride semiconductor devices over recent decades. However, the exact magnitude and orientation of polarization remain highly debated, as significant discrepancies persist among different theoretical approaches and experiments. Therefore, we combine off-axis electron holography with surface potential calibration and self-consistent electrostatic modeling to directly measure quantitatively polarization changes at InxGa1−xN/GaN interfaces. The results reveal a pronounced nonlinear, cubic dependence of spontaneous polarization on indium composition responsible for theoretical overestimation of polarization changes. Moreover, we show that only a layered hexagonal reference phase, rather than the zinc-blende phase, provides an accurate description of the experimental bowing of spontaneous polarization and hence a consistent theoretical framework of polarization in group-III nitrides. These results reconcile experiment and theory and provide a reliable basis for polarization engineering in InGaN alloys.

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Phys. Rev. B 113, 155302– Published 3 April, 2026
  • Received 5 November 2025
  • Accepted 9 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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