<i>In-operando</i> and non-destructive analysis of the resistive switching in the Ti/HfO₂/TiN-based system by hard x-ray photoelectron spectroscopy

Abstract

Resistive switching in Ti/HfO2/TiN was investigated in-operando by hard x-ray photoelectron spectroscopy. In comparison with the virgin-state, ON- and OFF-states show enhanced Ti/TiOx/HfO2 interface oxidation, resulting from an oxygen-gettering activity of Ti. The formed TiOx layer acts in the resistive switching process as an oxygen reservoir in exchange with the non-stoichiometric HfO2−δ. A Ti1+/Ti3+ valence change redox reaction occurs between OFF- and ON-states. The peak shifts are attributed to space charge potentials created by the varying oxygen vacancy concentration at the interface. A push-pull model of oxygen vacancies as a function of voltage polarity is proposed to describe the mechanism.