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arXiv · 2605.15568

Local distortions as a source of piezoelectric/stiffness decoupling in B-doped AlScN

Laszlo Wolf·Geoff L. Brennecka·Vladan Stevanović
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Abstract

We present a first-principles analysis of the wurtzite pseudo-ternary (Al,Sc,B)N to elucidate the structural origin of a decoupling between stiffness $C_{33}$ and piezoelectric response $e_{33}$ upon boron incorporation, using DFT-relaxed 100-atom special quasirandom structures across a broad composition range. Pair distribution function analysis reveals interstitial threefold-coordinated boron atoms that have displaced from the tetrahedral cation site. Direct structural analysis establishes their preferential orientation along the $c$-axis and identifies a scandium-activated creation mechanism. The vertical coordination asymmetry of each cation is quantified through a site-specific axial asymmetry ratio (AAR), showing that boron incorporation progressively symmetrizes the Sc environment. Correlation with Born effective charges demonstrates that this symmetrization is the mechanism behind the piezoelectric enhancement.

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Laszlo Wolf, Geoff L. Brennecka, Vladan Stevanović. 2026-05-15. Local distortions as a source of piezoelectric/stiffness decoupling in B-doped AlScN. https://arxiv.org/abs/2605.15568

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