A novel ferroelectric memristor enabling NAND-type analog memory characteristics

Abstract

Interfacial conduction had been confirmed at the surface of ferroelectric thin film owing to the extremely high charge density over 1014 cm−2 [1]. The effect is of interest because it may be used to make a unique memristor [2] (or memistor [3]). The nonvolatile nature of memristor makes it an attractive candidate for the next-generation memory technology. Recently, we have demonstrated the conductivity modulation of the interface between two oxides, ZnO and PZT, in a ferroelectric gate field-effect transistor (FeFET) [4,5], which is applicable for a nonvolatile memory. In this study, we demonstrate an Oxide Memory (OxiM) transistor as a new type of FeFET, provided with dual (top & bottom) gate, which can memorize the channel-conductance with the dynamic range over 105. By using serially-connected OxiM transistors, we were successful in fabricating NAND memory circuit with a retention time over 3.5 months. Since the ferroelectric polarization can be modulated continuously by the gate voltage, note that multi-valued data can be memorized in an OxiM transistor. This present new transistor is implemented by all oxide-based thin films, which include SrRuO 3 (SRO: bottom gate electrode), Pb(Zr,Ti)O 3 (PZT: ferroelectric), ZnO (semiconductor), and SiON (gate insulator).