Fig. 3
From: Harnessing ferroelectric domains for negative capacitance
The negative capacitance (NC)-based amplifying circuit and its characteristics. a The device has a substrate-deposited Big Mac structure comprising the ferroelectric (FE) (carrying up- and down-polarization domains, shown by the red and dark blue, respectively and separated by the green domain wall (DW)), and the dielectric (DE) (light blue) nanoplatelets. The FE and DE layers are confined between the three-parts electrode shown in orange, the top, intermediate, and bottom ones. The substrate is shown by the blue-gray. The top electrode, the strained uniaxial FE layer, and the intermediate electrode constitute the FE capacitor. The negative capacitance stems from the displacement of the DW in the FE capacitor. The DE capacitor comprises the ultrahigh-ε material. The bottom electrode is grounded. The input voltage, Vin, is applied to the cover top electrode. The output voltage, Vout, is collected from the DE capacitor and exceeds the input voltage, Vout > Vin. b The equivalent scheme of the circuit with Cf < 0 corresponding to the FE and Cd > 0 corresponding to the DE capacitors. c The plots Vout(Vin) corresponding to different radii of PbTiO3 nanodots contain three distinct segments: (i) linear parts which correspond to the displacing DW and reflect the amplifying effect (since the curves lie above the bissectrix Vout = Vin), (ii) the reverse parts corresponding to the unstable DW, and (iii) the flattened positive-slope-parts corresponding to the monodomain state response. The inset demonstrates the differential body factors, m = (dVout/dVin)−1, plotted as a function of Vin
