A dual channel ferroelectric-gate field-effect transistor

We demonstrate here an oxide memory (OxiM) transistor as a new type of ferroelectric-gate field-effect transistor (FeFET), provided with a dual (top and bottom) channel, which can memorize channel-conductance with a dynamic range exceeding 10⁴. This new transistor consists entirely of oxide-based thin films: SrRuO₃ (bottom gate electrode), Pb(Zr,Ti)O₃ (ferroelectric), ZnO (semiconductor), and SiON (gate insulator). A notable feature of the OxiM transistor is that two types of FET, such as a top gate-type TFT (top-TFT) and a bottom gate-type FeFET (bottom-FeFET), are stacked with a conduction layer of thin ZnO film in common. The channel conductance of the top-TFT and the bottom-FeFET can be controlled independently by the top gate and the bottom gate, respectively. We were successful in fabricating a NAND memory circuit using serially connected OxiM transistors. The dual gate structure allows disturb-free reading.