Manipulation of thin metal film morphology on weakly interacting substrates via selective deployment of alloying species
Résumé
We demonstrate a versatile concept for manipulating morphology of thin (≤25 nm) noble-metal films on weakly interacting substrates using growth of Ag on SiO 2 as a model system. The concept entails deployment of minority metallic (Cu, Au, Al, Ti, Cr, and Mo) alloying species at the Ag-layer growth front. Data from in situ and real-time monitoring of the deposition process show that all alloying agents—when deployed together with Ag vapor throughout the entire film deposition—favor two-dimensional (2D) growth morphology as compared to pure Ag film growth. This is manifested by an increase in the substrate area coverage for a given amount of deposited material in discontinuous layers and a decrease of the thickness at which a continuous layer is formed, though at the expense of a larger electrical resistivity. Based on ex situ microstructural analyses, we conclude that 2D morphological evolution under the presence of alloying species is predominantly caused by a decrease of the rate of island coalescence completion during the initial film-formation stages. Guided by this realization, alloying species are released with high temporal precision to selectively target growth stages before and after coalescence completion. Pre-coalescence deployment of all alloying agents yields a more pronounced 2D growth morphology, which for the case of Cu, Al, and Au is achieved without compromising the Ag-layer electrical conductivity. A more complex behavior is observed when alloying atoms are deposited during the post-coalescence growth stages: Cu, Au, Al, and Cr favor 2D morphology, while Ti and Mo yield a more pronounced three-dimensional morphological evolution. The overall results presented herein show that targeted deployment of alloying agents constitutes a generic platform for designing bespoken heterostructures between metal layers and technologically relevant weakly interacting substrates.
Domaines
- Mécanique des fluides [physics.class-ph]
- Matériaux et structures en mécanique [physics.class-ph]
- Acoustique [physics.class-ph]
- Automatique / Robotique
- Electromagnétisme
- Milieux fluides et réactifs
- Energie électrique
- Thermique [physics.class-ph]
- Vibrations [physics.class-ph]
- Physique mathématique [math-ph]
- Physique Quantique [quant-ph]
- Acoustique [physics.class-ph]
- Biomécanique [physics.med-ph]
- Matériaux
- Polymères
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