Artificial Modulation of Ferroelectric Thin Films into Antiferroelectric through H⁺ Implantation for High-Density Charge Storage

Hydrogen ions are implanted into Pb(Zr_0.3Ti_0.7)O₃ thin films at the energy of 40keV with a flux of 5×10¹⁴ions/cm². Pseudo-antiferroelectric behaviour in the implanted thin films is observed, as confirmed by the measurements of polarization versus electric hysteresis loops and capacitance versus voltage curves. X-ray diffraction patterns show the film structures before and after H⁺ implantation both to be perovskite of a tetragonal symmetry. These findings indicate that hydrogen ions exist as stable dopants within the films. It is believed that the dopants change domain-switching behaviour via the boundary charge compensation. Meanwhile, time dependence of leakage current density after time longer than 10s indicates the enhancement of the leakage current nearly in one order for the implanted film, but the current at time shorter than 1s is mostly the same as that of the original film without the ionic implantation. The artificial tailoring of the antiferroelectric behaviour through H⁺ implantation in ferroelectric thin films is finally proven to be achievable for the device application of high-density charge storage.