Structural and electrical characterization of Ar+ irradiated TiO2 thin films

Transition metal oxide thin films, like TiO2, which show a redox-based switching process between two or more resistance levels, are promising candidates for future memory storage devices.
They are extensively studied to get a better understanding of the role of mobile oxygen ions and/or oxygen vacancies for structural changes and electronic transport inside the films.
A defective, nonstoichiometric TiO2-x layer can act as a reservoir for oxygen vacancies and improves the switching characteristics. Such a layer was introduced into the virgin TiO2 film by low energy Ar+ irradiation with different energies and fluencies to modulate the depths and level of the defective region. The impact of the irradiation to the surface morphology and crystal structure was monitored by AFM and TEM measurements and was found to be surface smoothing and amorphization. The role of the preferential sputtering of oxygen to the stoichiometry of the film was investigated with TRIDYN simulations. Electrical properties of the irradiated films were characterized by I-V and C-V measurements and are related to the structural changes caused by the Ar+ irradiation.

The project is funded by the Initiative and Networking Fund of the Helmholtz Association (Virtual Institute Memriox, VH-VI-422).