Molecular Beam Epitaxy of Al(1-x)Sc(x)N Nanowires: Towards Group-III Nitride Piezoelectric Nanogenerators with Enhanced Response
Abstract
We study the molecular beam epitaxy of self-assembled Al1−xScxN nanowires on conductive TiN layers and demonstrate their application in piezoelectric nanogenerators. Wurtzite Al1−xScxN nanowires with uniform Sc incorporation are grown across a wide composition range (0<x<0.35). At substrate temperatures below 700 ∘C, these nanowires exhibit an inversely tapered morphology, whereas higher temperatures favor the nucleation of additional branches due to a phase separation of Al1−xScxN into wurtzite AlN and rock-salt ScN. Phase-pure Al1−xScxN nanowires are integrated into vertical nanogenerators, where the metallic TiN substrate serves as bottom electrode. The fabricated polymer-nanowire composite devices achieve effective piezoelectric charge coefficients of up to 8.5 pC N−1 at x=0.32, thus exceeding the piezoelectric response of bulk AlN by nearly a factor of two. Although the charge response remains lower compared to Al1−xScxN thin films, the reduced effective dielectric permittivity of the nanowire-polymer composites compensates the reduction in piezoelectric charge coefficient, eventually yielding a higher voltage response and comparable energy harvesting efficiency. Finally, effective medium modeling reveals that the device architecture is the primary factor limiting performance, providing general design principles for highly efficient nanowire-based piezoelectric energy harvesters.
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BibTeX
@misc{notarangelo2026molecular,
title = {{Molecular Beam Epitaxy of Al(1-x)Sc(x)N Nanowires: Towards Group-III Nitride Piezoelectric Nanogenerators with Enhanced Response}},
author = {Adriano Notarangelo and Rudeesun Songmuang and Mostafa Saleh and Natthawadi Buatip and Ileana Florea and Philippe Vennéguès and Aidan F. Campbell and Hans Tornatzky and Jonas Lähnemann and Thomas Auzelle and Lutz Geelhaar and Oliver Brandt and Philipp M. John},
howpublished = {HAL},
year = {2026},
month = jul,
eprint = {2602.12956},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05794470v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Molecular Beam Epitaxy of Al(1-x)Sc(x)N Nanowires: Towards Group-III Nitride Piezoelectric Nanogenerators with Enhanced Response
AU - Adriano Notarangelo
AU - Rudeesun Songmuang
AU - Mostafa Saleh
AU - Natthawadi Buatip
AU - Ileana Florea
AU - Philippe Vennéguès
AU - Aidan F. Campbell
AU - Hans Tornatzky
AU - Jonas Lähnemann
AU - Thomas Auzelle
AU - Lutz Geelhaar
AU - Oliver Brandt
AU - Philipp M. John
PY - 2026
DA - 2026/07/14
PB - HAL
UR - https://hal.science/hal-05794470v1
AB - We study the molecular beam epitaxy of self-assembled Al1−xScxN nanowires on conductive TiN layers and demonstrate their application in piezoelectric nanogenerators. Wurtzite Al1−xScxN nanowires with uniform Sc incorporation are grown across a wide composition range (0<x<0.35). At substrate temperatures below 700 ∘C, these nanowires exhibit an inversely tapered morphology, whereas higher temperatures favor the nucleation of additional branches due to a phase separation of Al1−xScxN into wurtzite AlN and rock-salt ScN. Phase-pure Al1−xScxN nanowires are integrated into vertical nanogenerators, where the metallic TiN substrate serves as bottom electrode. The fabricated polymer-nanowire composite devices achieve effective piezoelectric charge coefficients of up to 8.5 pC N−1 at x=0.32, thus exceeding the piezoelectric response of bulk AlN by nearly a factor of two. Although the charge response remains lower compared to Al1−xScxN thin films, the reduced effective dielectric permittivity of the nanowire-polymer composites compensates the reduction in piezoelectric charge coefficient, eventually yielding a higher voltage response and comparable energy harvesting efficiency. Finally, effective medium modeling reveals that the device architecture is the primary factor limiting performance, providing general design principles for highly efficient nanowire-based piezoelectric energy harvesters.
ER -