Proton redistribution and pseudoantiferroelectricity in H+ implanted Pb(Zr,Ti)O3 thin films

Abstract

Hydrogen ions were implanted into 500-nm-thick Pb(Zr,Ti)O3 ferroelectric thin films with different doses and energies. An antiferroelectric behavior was confirmed in the implanted thin films with proper H+ injection energies from independent measurements of polarization-electric hysteresis loops and capacitance-voltage curves. With the increase in the H+ doping concentration and implanting energy up to 25 keV, the characteristic pseudoantiferroelectric behavior becomes more evident in the films along with the concomitant reduction in the remnant polarization. However, the above antiferroelectricity is weakened for the restoration of a preferred ferroelectric state, once the implanting energy is higher than 35 eV. The consequent “Trim94” simulation of the H+ distribution as well as the induced oxygen vacancies (VO⋅⋅) indicates the almost linear shift in the depth for the maximum charge density within the film with the enhanced implanting energy until the depth moves out of the film thickness above 40 keV. Beyond the antiferroelectric dependence on the implanting energy in thin films, the previous ferroelectric state can also be rejuvenated under a bipolar-field stressing through the redistribution of the H+ and VO⋅⋅ concentrations. The rejuvenation process is accelerated upon heating due to the increased charge mobility. The doping charges are immobile during short-time domain switching but movable under a long-time negative/positive field with the estimated activation energy of 0.23/0.29 eV. This study implies the potential application of high-density charge storage of the implanted ferroelectric capacitor with the property comparable to a genuine antiferroelectric capacitor.