In Situ Thermal Imaging of Threshold Switching Devices

Negative Differential Resistor (NDR) devices based on Metal Oxide Metal (MOM) junctions are good candidates for the development of high-density memory selectors, and are also being considered as a building block for the development of neuromorphic hardware architectures [1, 2]. We will demonstrate through two case studies that the development of in situ Scanning Thermal Microscopy (SThM) experiments is well suited to the characterization of threshold switching devices whose operating principle relies essentially on electro-thermal effects. The first case study will focus on the observation and analysis of current line redistribution in niobium oxide devices [3]. The second case study will focus on devices based on vanadium oxide V₃O₅, which exhibits an insulator to metal transition (IMT) around 420K [4]. Analysis of SThM images taken at different operating points enables us to observe the initiation of NDR behavior at a temperature well below the transition temperature of the V₃O₅ material. This result confirms a theory according to which the initiation of NDR behavior is essentially attributed to the temperature dependence of the conductivity of the insulating phase of V₃O₅, and not directly to the IMT. In addition to confirming existing theories, SThM cartographies enable us to develop multiphysics finite element models, and open the way to thermal management of the studied structures for a global control of device operation.<br/><br/><br/><br/>Références<br/>[1] Goodwill, J.M., Ramer, G., Li, D., B. D. Hoskins, G. Pavlidis, J. J. McClelland, A. Centrone, J. A. Bain & M. Skowronski, “Spontaneous current constriction in threshold switching devices” Nat Commun 10, 1628 (2019). https://doi.org/10.1038/s41467-019-09679-9<br/>[2] M Drouhin, S Li, M Grelier, S Collin, F Godel, RG Elliman, B Dlubak, Juan Trastoy, Damien Querlioz, Julie Grollier, “Characterization and modeling of spiking and bursting in experimental NbOx neuron”, Neuromorphic Computing and Engineering 2 (4), 044008 (2022). https://doi.org/10.1088/2634-4386/ac969a<br/>[3] SK Nandi, E Puyoo, SK Nath, D Albertini, N Baboux, SK Das, T Ratcliff, R G Elliman, “High Spatial Resolution Thermal Mapping of Volatile Switching in NbOx-Based Memristor Using In Situ Scanning Thermal Microscopy”, ACS Applied Materials & Interfaces 14 (25), 29025-29031 (2022). https://doi.org/10.1021/acsami.2c06870<br/>[4] SK Das, SK Nandi, CV Marquez, A Rúa, M Uenuma, E Puyoo, SK Nath, D Albertini, N Baboux, T Lu, Y Liu, T Haeger, R Heiderhoff, T Riedl, T Ratcliff, R G Elliman, “Physical Origin of Negative Differential Resistance in V3O5 and Its Application as a Solid-state Oscillator”, Advanced Materials, 2208477 (2022). https://doi.org/10.1002/adma.202208477