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

Jonathan M Goodwill; Abhishek A Sharma; Dasheng Li; James A Bain; Marek Skowronski

doi:10.1021/acsami.6b16559

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

ACS Appl Mater Interfaces. 2017 Apr 5;9(13):11704-11710. doi: 10.1021/acsami.6b16559. Epub 2017 Mar 21.

Authors

Jonathan M Goodwill¹, Abhishek A Sharma², Dasheng Li¹, James A Bain², Marek Skowronski¹

Affiliations

¹ Department of Materials Science and Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
² Department of Electrical and Computer Engineering, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.

PMID: 28293945
DOI: 10.1021/acsami.6b16559

Abstract

Pulsed and quasi-static current-voltage (I-V) characteristics of threshold switching in TiN/TaO_x/TiN crossbar devices were measured as a function of stage temperature (200-495 K) and oxygen flow during the deposition of TaO_x. A comparison of the pulsed and quasi-static characteristics in the high resistance part of the I-V revealed that Joule self-heating significantly affected the current and was a likely source of negative differential resistance (NDR) and thermal runaway. The experimental quasi-static I-V's were simulated using a finite element electro-thermal model that coupled current and heat flow and incorporated an external circuit with an appropriate load resistor. The simulation reproduced the experimental I-V including the OFF-state at low currents and the volatile NDR region. In the NDR region, the simulation predicted spontaneous current constriction forming a small-diameter hot conducting filament with a radius of 250 nm in a 6 μm diameter device.

Keywords: Poole−Frenkel conduction; negative differential resistance; tantalum oxide; thermal runaway; threshold switch.