Impact-ionization-based resistive transition model for thin TiO_2 films

摘要

This study tries to reproduce the unipolar "forming" process and the "reset" process of the Pt/TiO_2/Pt capacitor. It is assumed that the impact ionization process triggers the "forming" process (so-called breakdown), and that the thermal energy generated by the conductive filament yields the "reset" process through the annihilation of oxygen vacancies. Simulations of I-V characteristics successfully reproduce the unipolar "forming" and "reset" processes. It is demonstrated that the "forming" voltage rises as TiO_2 film thickness increases, and that the "reset" voltage is insensitive to film thickness. The rise of the "forming" voltage stems from the increase in filament length and width. The insensitivity of "reset" voltage strongly suggests that the reaction energy of the oxygen ion with the vacancy is the critical parameter.