Size-driven transition of domain switching kinetics in LiNbO3 domain-wall memory

Repetitive erasure/creation of conducting domain walls between two parallel/antiparallel domains at bipolar write voltages enables the high storage density of a ferroelectric domain-wall memory. Generally, the domain switching kinetics is described by the Kolmogorov-Avrami-Ishibashi model on the basis of domain nucleation and growth without the consideration of distributive defect pinning energies. Here, mesa-like cells were etched from single-crystal LiNbO3 thin films bonded to SiO2/Si wafers, and Pt metal contacts were deposited at their sides. The abrupt off-to-on current jump occurs at a typical domain switching time for the cell in a lateral size above 111 nm, implying the non-Kolmogorov-Avrami-Ishibashi domain switching kinetics immune to the defect pinning effect. However, the domain switching time has a broad distribution for the cell below 49 nm, implying the defect-controlled domain switching mechanism. A new model is developed to describe the size-driven transition. The reliability tests of the memory show a fast operation speed (< 2 ns) and excellent reliability of on/off switching states for mass production.