Self-organized nanochannels in TiO₂ films for resistive switching device application

Future information technology depends on highly scalable, low power consuming simple and miniaturized memory devices. Among various approaches, the oxide-based resistive random access memory devices have shown their potential to fulfill these requirements. However, the success is driven by the switching mechanism. Among various models proposed, migration of oxygen vacancies (OVs) under electric filed is expected to play a key role in controlling the phenomenon. In order to understand this mechanism it is now important to introduce OV in oxide matrix in a controlled manner, especially for TiO₂ films, as this is considered to be a prospective candidate for future memory application. Here, I will show how 50 keV Ar⁺-ions can prepare self-organized nanochannels in TiO₂ films at a threshold fluence of 5×10¹⁶ ions/cm² at room temperature (RT). Given the X-ray diffraction measurements for revealing large scale structural modification of TiO₂ films with increasing ion fluence, I will discuss the evolution of nanochannels between voids by transmission electron microscopy (TEM). I will further show the evolution of near surface oxygen-deficient region by X-ray photoelectron spectroscopy. Following this, I will demonstrate the origin of local resistive switching behavior by conductive atomic force microscopy (c-AFM), and verify its potential by measuring current-voltage (I-V) characteristics in two-terminal Pt/TiO_x/TiO₂/Ti devices. I will discuss these experimental results in the light of OV migration through the self-organized nanochannels in TiO₂ layers (author)