[21p-H111-1~22] 6.3 Oxide electronics

[21p-H111-18] Humidity dependence of redox reactions at a Cu/Ta₂O₅ interface and its resistive switching behavior

〇Tohru Tsuruoka¹, Cedric Mannequin¹, Tsuyoshi Hasegawa², Masakzu Aono¹ (1.NIMS, 2.Waseda Uni.)

Keywords:oxide,redox reactions,moisture absorption

Redox reactions at the Cu/Ta₂O₅ interface and its resistive switching behavior under controlled humidity conditions have been investigated by means of cyclic voltammetry (CV) and current-voltage (I-V) measurements. Under positive bias to the Cu electrode, Cu is preferentially oxidized to Cu²⁺ and then to Cu⁺. Subsequent negative bias causes a reduction of the oxidized Cu ions at the interface. It was found that CV curves change drastically, from 5 to 85 %, with varied relative humidity (RH) levels. At higher RH levels, the ion concentrations and diffusion coefficients, estimated from the CV curves, suggest increased redox reaction rates and a significant contribution of proton conduction to the ionic transport. The I-V measurements showed a transition from nonvolatile to volatile switching with increasing RH. These results indicate the importance of moisture absorption by the matrix oxide film in understanding and controlling the resistive switching behavior of a Cu/Ta₂O₅/Pt structure.