Room-temperature deposition of a poling-free ferroelectric AlScN film by reactive sputtering

Crystallographic characterization and the ferroelectric properties of 50 nm-thick sputter-deposited Al0.78Sc0.22N films deposited at room temperature (RT) and 400 °C are investigated. c-axis oriented growths were confirmed by x-ray diffraction patterns with rocking curve measurements for both samples. Al0.78Sc0.22N films were found to grow in the c-axis direction and showed poling-free ferroelectric properties, which are advantageous for practical memory and piezoelectric applications. Although the metal-ferroelectric-metal (MFM) capacitors represent low switching cycle endurance, MFM capacitors revealed remnant polarization (Pr) of 70 μC/cm2 and 113 μC/cm2 for RT- and 400 °C-deposited samples, respectively. Ferroelectric films with low-temperature process capability can open a wide range of applications.