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 ‐In 2 Se 3 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.