Writing‐Speed Dependent Thresholds of Ferroelectric Domain Switching in Monolayer α‐In₂Se₃

Abstract

An electrical‐biased or mechanical‐loaded scanning probe written on the ferroelectric surface can generate programmable domain nanopatterns for ultra‐scaled and reconfigurable nanoscale electronics. Fabricating ferroelectric domain patterns by direct‐writing as quickly as possible is highly desirable for high response rate devices. Using monolayer α‐In2Se3 ferroelectric with ≈1.2 nm thickness and intrinsic out‐of‐plane polarization as an example, a writing‐speed dependent effect on ferroelectric domain switching is discovered. The results indicate that the threshold voltages and threshold forces for domain switching can be increased from −4.2 to −5 V and from 365 to 1216 nN, respectively, as the writing‐speed increases from 2.2 to 10.6 µm s−1. The writing‐speed dependent threshold voltages can be attributed to the nucleations of reoriented ferroelectric domains, in which sufficient time is needed for subsequent domain growth. The writing‐speed dependent threshold forces can be attributed to the flexoelectric effect. Furthermore, the electrical‐mechanical coupling can be employed to decrease the threshold force, achieving as low as ≈189±41 nN, a value smaller than those of perovskite ferroelectric films. Such findings reveal a critical issue of ferroelectric domain pattern engineering that should be carefully addressed for programmable direct‐writing electronics applications.

Large‐Area Growth of Ferroelectric 2D γ‐In2Se3 Semiconductor by Spray Pyrolysis for Next‐Generation Memory

“…Clear peaks corresponding to In3d and Se3d are observed, confirming the chemical bonding of In and Se. [28] The absence of the O1s peak demonstrates the absence of oxygen in the middle of film. Figure 1g shows a cross-sectional transmission electron microscope (TEM) image of the FeS-FET.…”