Modified Sawyer-Tower Circuit for characterization of negative-capacitance effects of ferroelectric thin films

Abstract

Recently the low energy-consuming electronic devices have become popular due to the rapid development of smart phones and Internet of Things For example negative capacitance FET (NC-FET) was investigated as a potential candidate thanks to its steeper subthreshold swing (< 60 mV/dec) compared to traditional Si-based FETs allowing a lower threshold voltage during FET operation However the negative capacitance characteristic occurs only in the ferroelectric polarization switching transient In order to characterize the negative capacitance properties we must figure out the ferroelectric behaviors of negative-capacitance thin films In this study the modified Sawyer-Tower circuit is employed to measure transient current change of strain-modulated BiFeO? and Pb[ZrxTi1-x]O? thin films during polarization switching We demonstrated the negative slope behavior in the outcome of ‘S’-shaped polarization-voltage characteristic regarded as one of the most important evidences of negative capacitance effect by Landau–Ginzburg–Devonshire (LGD model) The circuit design is improved by considering capacitance to be loaded in the measured circuit In this way the accomplishment of direct measuring the ferroelectric behaviors and negative-capacitance effects of ferroelectric thin films renders huge benefits for developing further quantification analysis

Date of Award	2019
Original language	English
Supervisor	Yi-Chun Chen (Supervisor)