Nanoscale domain structures with a feature size down to 5 nm in lithium niobate thin film on silicon substrate

By employing the tip-field-induced domain direct-writing technique based on atomic force microscopy, periodically poled lithium niobate (PPLN) with a periodicity of 40 nm was successfully fabricated in a 30 nm-thick, z-cut congruent lithium niobate thin film on silicon substrate. Simultaneously, ferroelectric dot-domain arrays with a lateral dimension of a single dot domain of ∼5 nm and a minimum dot-to-dot domain spacing of ∼26 nm were also achieved, demonstrating an information-storage density of 3.7 Tbit/in2. In addition, in MgO-doped lithium niobate thin films, PPLN with a period of 50 nm and dot domains with a lateral dimension less than 40 nm were obtained. These achievements effectively facilitate the device miniaturization and performance improvement for domain-based applications such as ferroelectric domain memories in lithium niobate.