(001)-Oriented Sr:HfO₂ Ferroelectric Films Deposited by a Flexible Chemical Solution Method

Remnant polarization values of ferroelectric HfO₂-based films depend on proper control of the polar orthorhombic phase crystallization and the orientation of the polar domains. Most of the best quality films reported so far are (111)-oriented. While the largest polarization is expected in (001)-oriented films, with the polar axis out of the plane, such orientation is far less common. This paper demonstrates that highly (001)/(010)-oriented heterostructures of Sr:HfO₂ on Pt(111)-buffered Si can be attained in layered films deposited by a recently reported chemical solution deposition route. The oriented films display the short c-axis out of plane, giving place to a longer a lattice in plane. By tailoring the duration of rapid thermal processing, such oriented films produce highly ferroelectric, leakage-free capacitors. After wake-up cycling, a remnant polarization of 17 μC/cm², which is the highest reported for this dopant and technique, was achieved. Even though optimization is still needed to improve the electrical cyclability, our facile approach produces high-k, highly oriented Sr:HfO₂ films, through chemical deposition and annealing, and shows that the crystal orientations and phase purity of HfO₂-based films can be further optimized by cost-effective chemical methods.