On the origin of bistable resistive switching in metal organic charge transfer complex memory cells

Electrical characteristics of Cu:tetracyanoquinodimethane (TCNQ) devices with different electrodes were studied. The comparison of impedance spectroscopic measurements on devices with Al and Pt top electrodes proved the existence of a high resistive interface layer between Cu:TCNQ and Al. An equivalent circuit was modeled and the resulting values suggest that the interface layer is composed of naturally formed aluminum oxide. Devices with deliberately formed aluminum oxide and without Cu:TCNQ were fabricated and revealed a similar behavior. The authors propose that the switching effect in Cu:TCNQ thin film devices is a Cu ion based electrochemical effect occurring in a thin aluminum oxide layer.