No‐Heating Deposition of Ferroelectric x%YO1.5–(100−x%)(Hf1−yZry)O2 Films

The no‐heating deposition of x%YO1.5–(100−x%)(Hf1−yZry)O2 (x = 0−0.09, y = 0, 0.25, 0.50, and 1) is achieved using a radio‐frequency magnetron sputtering method. To investigate the crystal structure and ferroelectric properties, epitaxial films are grown on (111)‐oriented indium tin oxide (ITO)/(111) Y‐stabilized zirconia (YSZ) substrates. The ferroelectric orthorhombic phase is obtained for the 5–7%YO1.5–95–93%HfO2 and 5%YO1.5–95% (Hf0.75Zr0.25)O2 films. The field‐induced phase transition from tetragonal to orthorhombic is confirmed for the 8%YO1.5–92%HfO2 and 5%YO1.5–95%(Hf0.50Zr0.50)O2 films. The remnant polarization (Pr) and coercive field (Ec) are 12–19 μC cm−2 and 2,000–2,500 kV cm−1, respectively. The piezoelectric response of 1 μm thick films is investigated for 6%YO1.5–94% HfO2, 7%YO1.5–93%HfO2, and 5%YO1.5–95%(Hf0.50Zr0.50)O2 films, which have piezoelectric coefficients (d33) of 1.0, 3.3, and 5.0 pm V−1, respectively. These results show no‐heating deposition of x%YO1.5–(100−x%)(Hf1−yZry)O2 films with ferroelectric and piezoelectric properties.