(Keynote) Atomic Scale and Interface Interactions in Redox-Based Resistive Switching Memories

Controlling electrochemical processes at interfaces or within thin films at the atomic scale is a key factor for further development of future nanoelectronics and information technology. This aspect becomes even more important considering concepts beyond conventional data storage like neuromorphic and memristive systems, demonstrating learning abilities and allowing logic operations.

Redox-based resistive switching memories (ReRAM) are major candidates to fulfil all requirements for low power consumption, ultrafast operation, high information density and non-volatility. Their metal/solid-electrolyte/metal structure makes the preparation process simple and compatible with current CMOS technology. In ReRAMs, the solid electrolyte thickness varies in the range between few nanometers up to some ten nanometers. Due to the small dimensions, the high electric fields in the order of E ~ 10⁸ Vm^–1, and current densities of j ~ 10⁹ Acm^–2, the interface regions are dynamically changing as a function of the thermodynamic and operation conditions. Deposited as nanoscale films, even macroscopic insulating materials like SiO₂ and Ta₂O₅ are able to conduct ions, and electrochemical measurements well known from the liquid electrochemistry can be performed.

The talk gives an overview on the current state-of-the-art knowledge on redox-based resistive switching ReRAMs, focusing on the electrochemical dynamics at the metal/solid-electrolyte interfaces of nanoscaled thin films and quantum effects. The electrochemical kinetics during formation of nanofilaments will be discussed along with influence of the local environment and the generic relevance of the counter charges. The relation of these studies to the more fundamental issue of describing the microscopic electrochemical processes at the atomic scale will be emphasized.