No‐Heating Deposition of Ferroelectric x %YO 1.5 –(100− x %)(Hf 1− y Zr y )O 2 Films

The no‐heating deposition of x %YO 1.5 –(100− x %)(Hf 1− y Zr y )O 2 ( 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%YO 1.5 –95–93%HfO 2 and 5%YO 1.5 –95% (Hf 0.75 Zr 0.25 )O 2 films. The field‐induced phase transition from tetragonal to orthorhombic is confirmed for the 8%YO 1.5 –92%HfO 2 and 5%YO 1.5 –95%(Hf 0.50 Zr 0.50 )O 2 films. The remnant polarization ( P r ) and coercive field ( E c ) 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%YO 1.5 –94% HfO 2 , 7%YO 1.5 –93%HfO 2 , and 5%YO 1.5 –95%(Hf 0.50 Zr 0.50 )O 2 films, which have piezoelectric coefficients ( d 33 ) of 1.0, 3.3, and 5.0 pm V −1 , respectively. These results show no‐heating deposition of x %YO 1.5 –(100− x %)(Hf 1− y Zr y )O 2 films with ferroelectric and piezoelectric properties.