Passive voltage amplification in non-leaky ferroelectric–dielectric heterostructure

This work presents the effect of ferroelectric thickness variation on properties (negative capacitance stabilisation, voltage amplification and capacitance enhancement) of ferroelectric–dielectric (FE–DE) heterostructure. For a better understanding of heterostructure, the study has analysed isolated ferroelectric capacitor first. Results clearly indicate the unstable nature of negative capacitance in ferroelectric capacitor. This negative capacitance can be stabilised by adding a dielectric capacitor in series with ferroelectric capacitor. Dielectric capacitor not only stabilises the negative capacitance state but is also responsible for the increase in capacitance of heterostructure. Afterwards dynamic response of FE–DE hetrostructure is studied. It is observed that thickness has strong dependence on ferroelectric parameters. With the increase in ferroelectric thickness, ferroelectric capacitance decreases and hence leads to voltage amplification. However, ferroelectric thickness should not be increased beyond critical thickness, as beyond critical thickness voltage amplification cannot be achieved without hysteresis.