Electroforming and Switching in Oxides of Transition Metals: The Role of Metal–Insulator Transition in the Switching Mechanism

• Published in: Journal of solid state chemistry 1996-02, Vol.122 (1), p.95-99
• Main Authors: Chudnovskii, F.A., Odynets, L.L., Pergament, A.L., Stefanovich, G.B.
• Format: Article
• Language: English
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1996.0087

Electroforming and switching effects in sandwich structures based on anodic films of transition metal oxides (V, Nb, Ti, Fe, Ta, W, Zr, Hf, Mo) have been studied. After being electroformed, some materials exhibited current-controlled negative resistance with S-shapedV–Icharacteristics. For V, Fe, Ti, and Nb oxides, the temperature dependences of the threshold voltage have been measured. As the temperature increased,Vthdecreased to zero at a critical temperatureT0, which depended on the film material. Comparison of theT0values with the temperatures of metal–insulator phase transition for some compounds (Tt= 120 K for Fe3O4, 340 K for VO2, ∼500 K for Ti2O3, and 1070 K for NbO2) showed that switching was related to the transition in the applied electric field. Channels consisting of the above-mentioned lower oxides were formed in the initial anodic films during the electroforming. The possibility of formation of these oxides with a metal–insulator transition was confirmed by thermodynamic calculations.