So far, a few chemical solution routes for the fabrication of ferroelectric HfO2 films have been reported. Most of them employ precursors, solvents or additives that are considered difficult to...

Electronic conduction along individual domain walls (DWs) is reported in BiFeO 3 (BFO) and other nominally insulating ferroelectrics. DWs in these materials separate regions of differently oriented electrical polarization (domains) and are just a few atoms wide, providing self-assembled nanometric conduction paths. Herein, it is shown that electronic transport is possible also from wall-to-wall through the dense network of as-grown DWs in BFO thin films. Electric field cycling at different points of the network, performed locally by conducting atomic force microscopy (cAFM), induces resistive switching selectively at the DWs, both for vertical (single wall) and lateral (wall-to-wall) conduction. These findings are the first step toward investigating DWs as memristive networks for information processing and in-materio computing.

We present a study of the trade-off between the retention and variability of SrTiO3-based memristive devices. We identified the applied switching current and the device stoichiometry as main influence factors. We show that the SrO formation at the electrode interface, which has been revealed to improve the device retention significantly, is associated with an increased cycle-to-cycle and device-to-device variability. On the other hand, devices with homogeneous, Ti-terminated SrTiO3–Pt interfaces exhibit poor retention but the smallest variability. These results give valuable insights for the application of memristive SrTiO3 devices as non-volatile memory or in neural networks, where the control of variability is of key relevance.

So far, a few chemical solution routes for the fabrication of ferroelectric HfO2 films have been reported. Most of them employ precursors, solvents or additives that are considered difficult to handle, unstable, toxic, generally unfriendly with the environment and/or unsuitable for large scale industrial processes. In this work, we present a new effective chemical route for preparation of ferroelectric doped-HfO2 films. The solution is prepared from simple, stable, and available precursors, handled in an open atmosphere and requires no restrictive processing conditions. We used 5 at.% Ca as dopant of HfO2 to induce a maximum remnant polarization of 9.3 and 11.1 µC/cm2 for 54 and 90 nm thick Ca:HfO2 films, respectively. The current-electric field loops show intense and distinctive ferroelectric switching peaks and the corresponding ferroelectric loops show excellent saturation, which speaks of good device quality with low leakage. Crystallization and the wake-up of ferroelectricity in Ca:HfO2 films was attained by means of rapid thermal annealing at different temperatures and times in Ar:O2 atmosphere. In comparison to the thin films, thicker ones exhibited the highest remnant polarization at shorter annealing times, thus evidencing the need for precise control of thermal processing. The Ca:HfO2 films with thickness of 50 nm displayed a good balance between leakage and retention, maintaining the ferroelectric response above 105 cycles at 1 kHz. The developed precursor solution is promising for its use in spray-coating and ink-jet printing techniques.