Influence of mechanical compliance of the substrate on the morphology of nanoporous gold thin films

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Hauptverfasser: Shahriar, Sadi, Somayajula, Kavya, Winkeljohn, Conner, Mason, Jeremy, Seker, Erkin
Format: Preprint
Veröffentlicht: 2024
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author Shahriar, Sadi
Somayajula, Kavya
Winkeljohn, Conner
Mason, Jeremy
Seker, Erkin
author_facet Shahriar, Sadi
Somayajula, Kavya
Winkeljohn, Conner
Mason, Jeremy
Seker, Erkin
contents Nanoporous gold (np-Au) has found use in applications ranging from catalysis to biosensing where pore morphology plays a critical role in performance. While morphology evolution of bulk np-Au has been widely studied, knowledge about its thin film form is limited. This work hypothesizes that mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10s to 100s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to glass. Conversely, uniformly-distributed microscopic (100s of nanometers) cracks form in greater numbers in the np-Au films on glass than on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics.
format Preprint
id arxiv_https___arxiv_org_abs_2402_11694
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Influence of mechanical compliance of the substrate on the morphology of nanoporous gold thin films
Shahriar, Sadi
Somayajula, Kavya
Winkeljohn, Conner
Mason, Jeremy
Seker, Erkin
Materials Science
Applied Physics
Nanoporous gold (np-Au) has found use in applications ranging from catalysis to biosensing where pore morphology plays a critical role in performance. While morphology evolution of bulk np-Au has been widely studied, knowledge about its thin film form is limited. This work hypothesizes that mechanical compliance of the thin film substrate can play a critical role in the morphology evolution. Via experimental and finite-element-analysis approaches, we investigate the morphological variation in np-Au thin films deposited on compliant silicone (PDMS) substrates of a range of thicknesses anchored on rigid glass supports and compare those to the morphology of np-Au deposited on glass. More macroscopic (10s to 100s of microns) cracks and discrete islands form in the np-Au films on PDMS compared to glass. Conversely, uniformly-distributed microscopic (100s of nanometers) cracks form in greater numbers in the np-Au films on glass than on PDMS, with the cracks located within the discrete islands. The np-Au films on glass also show larger ligament and pore sizes possibly due to higher residual stresses compared to the np-Au/PDMS films. The effective elastic modulus of the substrate layers decreases with increasing PDMS thickness, resulting in secondary np-Au morphology effects including a reduction in macroscopic crack-to-crack distance, an increase in microscopic crack coverage, and a widening of the microscopic cracks. However, changes in the ligament/pore widths with PDMS thickness are negligible, allowing for independent optimization for cracking. We expect these results to inform the integration of functional np-Au films on compliant substrates into emerging applications, including flexible electronics.
title Influence of mechanical compliance of the substrate on the morphology of nanoporous gold thin films
topic Materials Science
Applied Physics
url https://arxiv.org/abs/2402.11694