  ScAlN is an emerging ferroelectric material that possesses large band gap,
strong piezoelectricity, and holds great promises for enhanced \chi^{(2)}
nonliearity. In this study, we demonstrate high-fidelity ferroelectric domain
switching and periodic poling of Al-polar ScAlN thin film epitaxially grown on
on c-axis sapphire substrate using gallium nitride as a buffer layer. Uniform
poling of ScAlN with periods ranging from 2 um to 0.4 um is realized. The
ability to lithographically control the polarization of epitaxial ScAlN
presents a critical advance for its further exploitation in ferroelectric
storage and nonlinear optics applications.
