Investigating contact resistance between WO_x and metal electrodes in ECRAMs via interface analysis.

Area of Science:

• Neuromorphic computing
• Materials science
• Solid-state electronics

Background:

• Resistive processing units are key in neuromorphic computing, overcoming von Neumann architecture limitations.
• Electrochemical random-access memories (ECRAMs) use ion movement for simultaneous data processing and memory storage.
• Contact resistance in WO_x-based ECRAMs is a critical, yet understudied, factor for device performance.

Purpose of the Study:

• To investigate and quantify the contact resistance between WO_x channels and various metal electrodes (W, Mo, Ni).
• To determine the electrical contact properties (Ohmic vs. Schottky) and interface characteristics.
• To identify the most suitable metal contact material for high-performance WO_x-based ECRAMs.

Main Methods:

• Fabrication of transmission line model (TLM) devices with WO_x channels and W, Mo, or Ni electrodes.
• Measurement and analysis of contact resistance and resistivity.
• Characterization of interfacial properties, including Schottky barrier height and metal oxidation layers.

Main Results:

• Tungsten (W) exhibited the lowest contact resistance with WO_x, followed by Nickel (Ni) and Molybdenum (Mo).
• W and Mo formed Ohmic contacts, while Ni formed a Schottky contact with a barrier height of 118 meV.
• Mo formed a 9 nm metal oxidation layer at the WO_x interface; W contact resistivity correlated with WO_x channel resistivity.

Conclusions:

• Tungsten (W) is identified as the most suitable contact material for WO_x-based ECRAMs due to its minimal contact resistance.
• Understanding contact properties is crucial for optimizing ECRAM performance in neuromorphic applications.
• The study provides essential data for designing next-generation resistive memory devices.