Flexible Inorganic Ferroelectric Thin Films for Nonvolatile Memory Devices

TLDR

Flexible nonvolatile devices are required for next‑generation wearable electronics, yet only organic ferroelectric materials have previously shown intrinsic flexibility on plastic substrates. By controlling the heating rate, ultrathin (30 nm) ferroelectric hafnia films were deposited on plastic, exhibiting 10 µC cm⁻² remnant polarization, retaining ferroelectricity under bending radii below 8 mm for 1000 cycles, and enabling a low‑voltage nonvolatile vertical organic transistor with projected 10‑year retention.

Abstract

Next‐generation wearable electronics call for flexible nonvolatile devices for ubiquitous data storage. Thus far, only organic ferroelectric materials have shown intrinsic flexibility and processability on plastic substrates. Here, it is shown that by controlling the heating rate, ferroelectric hafnia films can be grown on plastic substrates. The resulting highly flexible capacitor with a film thickness of 30 nm yields a remnant polarization of 10 µC cm −2 . Bending tests show that the film ferroelectricity can be retained under a bending radius below 8 mm with up to 1000 bending cycles. The excellent flexibility is due to the extremely thin hafnia film thickness. Using the ferroelectric film as a gate insulator, a low voltage nonvolatile vertical organic transistor is demonstrated on a plastic substrate with an extrapolated date retention time of up to 10 years.