TY - THES

T1 - Ductile Mo-Re thin films for flexible displays

AU - Hauser, Filipe

N1 - embargoed until 17-09-2021

PY - 2016

Y1 - 2016

N2 - Sputtered Mo films are nowadays widely used as thin films in display applications, e.g., for gate and source/drain metallization and data bus-lines in thin film transistor liquid crystal displays. However, due to their brittle behavior their usability in flexible displays, i.e. for an emerging market, is limited. In order to overcome this disadvantage, a strategy to improve the ductility of brittle Mo thin films by alloying with Re is explored within this work. A series of Mo-Re thin films with 50 nm thickness were deposited onto 50 µm thick polyimide substrates by magnetron co-sputtering from pure Mo and Re targets. Advanced in situ characterization methods were subsequently applied to investigate the electro-mechanical behavior of the films during deformation. Uniaxial tensile tests were performed under the light microscope to directly observe the fragmentation process and to determine the crack onset strain. In addition, the electro-mechanical response was evaluated by measuring the change in the electrical resistance during straining. Pure Mo thin films exhibited straight through-thickness cracks, which are characteristic for brittle films, while the Mo-Re films showed a more wavy crack path, indicating ductile deformation behavior. The addition of Re also significantly improved the electro-mechanical response of the Mo thin films, where the crack onset strain was increased considerably. In summary, alloying of Mo thin films with Re is a promising strategy to improve their ductility, which in turn can enable their utilization in flexible displays.

AB - Sputtered Mo films are nowadays widely used as thin films in display applications, e.g., for gate and source/drain metallization and data bus-lines in thin film transistor liquid crystal displays. However, due to their brittle behavior their usability in flexible displays, i.e. for an emerging market, is limited. In order to overcome this disadvantage, a strategy to improve the ductility of brittle Mo thin films by alloying with Re is explored within this work. A series of Mo-Re thin films with 50 nm thickness were deposited onto 50 µm thick polyimide substrates by magnetron co-sputtering from pure Mo and Re targets. Advanced in situ characterization methods were subsequently applied to investigate the electro-mechanical behavior of the films during deformation. Uniaxial tensile tests were performed under the light microscope to directly observe the fragmentation process and to determine the crack onset strain. In addition, the electro-mechanical response was evaluated by measuring the change in the electrical resistance during straining. Pure Mo thin films exhibited straight through-thickness cracks, which are characteristic for brittle films, while the Mo-Re films showed a more wavy crack path, indicating ductile deformation behavior. The addition of Re also significantly improved the electro-mechanical response of the Mo thin films, where the crack onset strain was increased considerably. In summary, alloying of Mo thin films with Re is a promising strategy to improve their ductility, which in turn can enable their utilization in flexible displays.

KW - Molybdenum-Rhenium thin films

KW - magnetron sputtering

KW - flexible displays

KW - fragmentation test

KW - electrical resistance

KW - Rhenium effect

KW - Molybdän-Rhenium Legierungsschichten

KW - Magnetronsputtern

KW - flexible Displays

KW - Fragmentierungstest

KW - elektrischer Widerstand

KW - Rheniumeffekt

M3 - Master's Thesis

ER -