Vertically integrated logic circuits constructed using ZnO-nanowire-based field-effect transistors on plastic substrates

ZnO-nanowire-based logic circuits were constructed by the vertical integration of multilayered field-effect transistors (FETs) on plastic substrates. ZnO nanowires with an average diameter of ~100 nm were synthesized by thermal chemical vapor deposition for use as the channel material in FETs. The ZnO-based FETs exhibited a high I_ON/I_OFF of >10⁶, with the characteristic of n-type depletion modes. For vertically integrated logic circuits, three multilayer FETs were sequentially prepared. The stacked FETs were connected in series via electrodes, and C-PVPs were used for the layerisolation material. The NOT and NAND gates exhibited large logic-swing values of ~93%. These results demonstrate the feasibility of three dimensional flexible logic circuits.