In-Memory Ferroelectric Differentiator

Summary

FeRAM based on passive crossbar array of ferroelectric P(VDF-TrFE) capacitorsFerroelectricity is a property of certain materials that exhibit spontaneous electric polarization that can be reversed by the external electric field14,15,16,17,18. Displacement currents due to polarization reversal can be detected when the applied electric field is higher than the coercive field13,19. The non-volatile nature of ferroelectric materials, coupled with their ability to gradually change polarization states in response to external stimuli, makes them excellent candidates for simulating biomimetic synaptic devices20,21,22,23 and for constituting in-memory computing hardware24,25,26,27,28,29,30,31. P(VDF-TrFE) is a leading organic ferroelectric material known for its superior ferroelectric characteristics, robust chemical stability and biocompatibility32,33,34. In this study, solution-processed ferroelectric P(VDF-TrFE) thin films with a molar composition of 70:30 are used to construct devices for FeRAM. The ferroelectric nature of these fabricated P(VDF-TrFE) films was validated by distinct butterfly-shaped amplitude hysteresis loops and 180°-reversed phase hysteresis loops observed using piezoresponse force microscopy (PFM) (Supplementary Fig. 1a). Reliable ferroelectric domains with reduced amplitude at domain boundaries, as illustrated in Supplementary Fig. 1b, and 180° phase rotation between adjacent domains, as shown in Supplementary Fig. 1c, can be efficiently created using an electrical writing process. As shown in Supplementary Fig. 2a, the atomic force microscope topography exhibits no noticeable macroscopic defects, pinholes, or visible cracks from atomic force microscope images. The root means square roughness is of ~1.25 nm as derived from Supplementary Fig. 2a, indicating that uniform and smooth P(VDF-TrFE) films are successfully obtained. The X-ray diffraction (XRD) pattern of the P(VDF-TrFE) films exhibit a distinct Bragg peak at 19.6° (Supplementary Fig. 2b), whi...