Substrate-dependent thermally driven morphological evolution of Pt0.9Ni0.1 thin films on sapphire and langasite
Abstract
We examine the thermal evolution of 100-nm-thick Pt0.9Ni0.1 alloy films on sapphire and langasite substrates with a 10-nm Zr adhesion layer. Sequential vacuum annealing from room temperature to 800 ∘C produces a substrate-dependent morphological pathway that is quantified by atomic force microscopy, image segmentation, height-distribution analysis, and effective coarsening metrics. Both types of films remain densely granular up to 400 ∘C, undergo a sharp coarsening transition between 400 and 600 ∘C, and evolve into coalesced faceted crystallites by 800 ∘C. The mean projected feature area increases from 7.84 × 102 to 1.09 × 105 nm2 on langasite and from 3.32 × 102 to 1.67 × 105 nm2 on sapphire. Sapphire therefore develops the larger faceted crystallites, while langasite exhibits the larger roughness maximum at 600 ∘C. Area distributions reveal that the 400-600 ∘C transition does not uniformly shift the initial granular population but instead replaces it with a distinct large-feature ensemble. Height and roughness measurements show a pronounced maximum at 600 ∘C, followed by partial smoothing at 800 ∘C, consistent with rapid coalescence followed by faceting-limited growth. An effective Arrhenius analysis based on Δ⟨ r2⟩, with ⟨ r2⟩ = ⟨ A⟩/π, identifies the 400-600 ∘C interval as the dominant coarsening window. These results show that the thermal stability of PtNi/Zr films on sapphire and langasite is governed by the coupled influence of alloy mobility, interfacial energetics, and substrate-dependent morphological selection.
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BibTeX
@misc{fiaz2026substratedependent,
title = {{Substrate-dependent thermally driven morphological evolution of Pt$_0.9$Ni$_0.1$ thin films on sapphire and langasite}},
author = {M. Awais Fiaz and M. Greenslit and R. J. Lad and Mauricio Pereira da Cunha and Luke Doucette and S. M. Hollen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.09909},
eprint = {2608.09909},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.09909},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Substrate-dependent thermally driven morphological evolution of Pt_0.9Ni_0.1 thin films on sapphire and langasite
AU - M. Awais Fiaz
AU - M. Greenslit
AU - R. J. Lad
AU - Mauricio Pereira da Cunha
AU - Luke Doucette
AU - S. M. Hollen
PY - 2026
DA - 2026/09/06
PB - arXiv
DO - 10.48550/arxiv.2608.09909
UR - https://arxiv.org/abs/2608.09909
AB - We examine the thermal evolution of 100-nm-thick Pt_0.9Ni_0.1 alloy films on sapphire and langasite substrates with a 10-nm Zr adhesion layer. Sequential vacuum annealing from room temperature to 800 ^∘C produces a substrate-dependent morphological pathway that is quantified by atomic force microscopy, image segmentation, height-distribution analysis, and effective coarsening metrics. Both types of films remain densely granular up to 400 ^∘C, undergo a sharp coarsening transition between 400 and 600 ^∘C, and evolve into coalesced faceted crystallites by 800 ^∘C. The mean projected feature area increases from 7.84 × 10^2 to 1.09 × 10^5 nm^2 on langasite and from 3.32 × 10^2 to 1.67 × 10^5 nm^2 on sapphire. Sapphire therefore develops the larger faceted crystallites, while langasite exhibits the larger roughness maximum at 600 ^∘C. Area distributions reveal that the 400-600 ^∘C transition does not uniformly shift the initial granular population but instead replaces it with a distinct large-feature ensemble. Height and roughness measurements show a pronounced maximum at 600 ^∘C, followed by partial smoothing at 800 ^∘C, consistent with rapid coalescence followed by faceting-limited growth. An effective Arrhenius analysis based on Δ⟨ r^2⟩, with ⟨ r^2⟩ = ⟨ A⟩/π, identifies the 400-600 ^∘C interval as the dominant coarsening window. These results show that the thermal stability of PtNi/Zr films on sapphire and langasite is governed by the coupled influence of alloy mobility, interfacial energetics, and substrate-dependent morphological selection.
ER -