Balancing the electro-mechanical and interfacial performance of Mo-based alloy films

Currently used Mo/Al/Mo electrodes in thin film transistor display technologies potentially limit the lifetime of flexible displays due to brittle fracture behavior. The aim of the current work is to improve the electro-mechanical behavior of these electrode stacks by alloying the Mo adhesion layer with suitable metals to increase its ductility, while maintaining their good electrical conductivity and adhesion. Magnetron sputtered Mo thin films, alloyed with Al, Nb or Ta, on flexible Polyimide substrates were tested with monotonic in situ uniaxial tensile tests to evaluate their respective fracture resistance, electrical behavior, and interface strength to the substrate. Among the tested alloys, Mo-Ta best combines low electrical resistivity with high crack onset strains and improved interface strength. Therefore, Mo-Ta shows the best prospects to substitute the Mo adhesion layers in display technologies to increase the performance and lifetime of flexible displays.