Thermodynamic driving force of transient negative capacitance of ferroelectric capacitors

Negative capacitance (NC) field-effect transistors have great potential as next-generation low-power transistors due to their ability to overcome the Boltzmann limit. However, the fundamental physical mechanism of negative capacitance (NC) has not yet been clarified. This paper investigates the thermodynamic driving force of transient NC in the series circuit of a resistor and ferroelectric capacitor (R–FEC). We find that the widely applied Landau–Khalatnikov theory, which describes the minimization of Gibbs free energy, has the limitation to understand transient NC. The thermodynamic driving force of the transient NC is the minimization of the difference between the elastic Gibbs free energy and electric polarization work. Moreover, we find that the appearance of transient NC phenomenon is not due to the widely accepted viewpoint that the ferroelectric polarization goes through the negative curvature region of elastic Gibbs free energy landscape (Ga). Instead, after the energy barrier of Ga disappears, the transient NC phenomenon appears when the electric field across the ferroelectric material reaches local maximum. Furthermore, our results show that this process depends on both the intrinsic parameters of the ferroelectric material and the extrinsic factors in the R–FEC circuit.