Capacitance Of Dielectric Layer Research Articles

Studies on the nonlinear dielectric response in ferroelectric–dielectric composite system

The nonlinear dielectric response (NDR) of Bi3.25La0.75Ti3O12–Al2O3 systems has been studied. To reveal the effects of the dielectric layer (DL) systematically, a method based on the equivalent circuit analysis and parametric study is proposed. The consistency between the calculated results and the experimental results manifests the validity of the method. In addition to the Rayleigh coefficients varying monotonically with the capacitance of DL, it is revealed that the slope between the real and the imaginary parts of the complex capacitance under different ac voltages is related to the relative loss values of DL and the ferroelectric layer. The frequency dependence of the NDR parameters is also discussed. The method established in this work is useful for research on the devices based on the ferroelectric–dielectric system and the ultra-thin ferroelectric films.

Solution-processable alumina: PVP nanocomposite dielectric layer for high-performance organic thin-film transistors

In this article, we have investigated the effect of nanocomposite gate dielectric layer built by alumina (Al2O3) and poly(4-vinyphenol) (PVP) with solution method which could enhance the dielectric capability and decrease the surface polarity. Then, we used modify layer to optimize the surface morphology of dielectric layer to further improve the insulation capability, and finally we fabricated the high-performance and low-voltage organic thin-film transistors by using this nanocomposite dielectric layer. The result shows that the devices with Al2O3:10%PVP dielectric layer with a modified layer exhibited a mobility of 0.49 cm2/Vs, Ion/Ioff ratio of 7.8 × 104, threshold voltage of − 1.2 V, sub-threshold swing of 0.3 V/dec, and operating voltage as low as − 4 V. The improvement of devices performance was owing to the good insulation capability, appropriate capacitance of dielectric layer, and preferable interface contact, smaller crystalline size of active layer.

Phase diagrams of single-domain ferroelectric-dielectric superlattices

Using the thermodynamic theory, the authors developed misfit strain-temperature phase diagrams of single-domain ferroelectric-dielectric superlattices grown on cubic substrates. Owing to internal electric fields appearing in such multilayers, the superlattice diagrams are expected to be very different from phase maps of homogeneous ferroelectric films. The calculations show, however, that this electrostatic effect does not change relative positions of phase transition lines. It only shifts the diagram as a whole along the line separating stability ranges of paraelectric phase and in-plane polarization state. The magnitude of this shift is governed by the capacitance of dielectric layer and the thickness of ferroelectric one.