Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

Abstract

Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

Microwave conductivity of ferroelectric domains and domain walls in a hexagonal rare-earth ferrite

“…It is now generally accepted that the prominent conductivity difference between domains and DWs is a norm rather than an exception 9 . Consequently, much effort has been made to demonstrate DW-based nanodevices 10 , such as nonvolatile memory 11,12 , field effect transistors (FETs) 13 , reconfigurable channels 14,15 , and DW-motion logics 16 . While many functionalities are achieved at zero (dc) or low frequencies, practical devices usually demand much higher operation frequencies.…”

Next-generation ferroelectric domain-wall memories: principle and architecture

“…Alternatively, information can be read from the tiny domain via the temporary generation of a high wall current near the film surface under the application of the in-plane read field (E) between the two top electrodes (TE1 and TE2). 15,16 Fig. 2b (left panel) shows an in-plane PFM phase image of two switched head-tohead 71°triangular domains in a (001) BiFeO 3 thin film, 16 where the in-plane polarization (P) intersects with E at an angle of α.…”

“…15,16 Fig. 2b (left panel) shows an in-plane PFM phase image of two switched head-tohead 71°triangular domains in a (001) BiFeO 3 thin film, 16 where the in-plane polarization (P) intersects with E at an angle of α. 17 The concomitant CAFM image presented in the inset shows the significantly higher electrical conductivity of the entire domain-wall region.…”

Domain-wall nanoelectronics in ferroelectric memory

“…1a), Jiang et al fabricated domain-wall nanodevice in multiferroic BiFeO 3 thin films by taking advantage of the parallel nanoelectrodes (Fig. 1b) [6]. The "0" and "1" states can be written and readout by creating or erasing the conducting domain walls with a high speed.…”