Electro-Thermal Model of Threshold Switching in TaO_x-Based Devices

Area of Science:

• Materials Science
• Electrical Engineering
• Solid State Physics

Background:

• Threshold switching in resistive memory devices is crucial for next-generation electronics.
• Understanding the physical mechanisms, particularly thermal effects, is key to device optimization.
• Titanium nitride/tantalum oxide/titanium nitride (TiN/TaOx/TiN) structures are promising for resistive switching applications.

Purpose of the Study:

• To investigate the influence of temperature and oxygen content on TiN/TaOx/TiN threshold switching.
• To differentiate between intrinsic switching behavior and thermal effects.
• To validate experimental findings with a comprehensive electro-thermal model.

Main Methods:

• Pulsed and quasi-static current-voltage (I-V) measurements were performed across a temperature range of 200-495 K.
• TaOx deposition oxygen flow was varied to study its impact on device characteristics.
• A finite element electro-thermal model was developed to simulate coupled current and heat flow.

Main Results:

• Joule self-heating was identified as a significant factor contributing to negative differential resistance (NDR) and thermal runaway in the high-resistance state.
• The electro-thermal model successfully reproduced experimental I-V curves, including the OFF-state and volatile NDR.
• Simulations predicted the formation of a narrow, hot conducting filament (250 nm radius) within the 6 μm device during NDR.

Conclusions:

• Joule heating plays a critical role in the observed threshold switching behavior and NDR in TiN/TaOx/TiN devices.
• The developed electro-thermal model provides a reliable tool for understanding and predicting device performance.
• The findings offer insights into the filamentary nature of conduction during switching events.