Metastable Rutile TiO <sub>2</sub> Growth on Non‐Lattice‐Matched Substrates via a Sacrificial Layer Strategy
Jihoon Jeon, Myoungsu Jang, S. H. Ye, Taeseok Kim, Sung‐Chul Kim, Sung Ok Won, Seong Keun Kim, Seong Keun Kim, Seong Keun Kim
Abstract
Abstract Metastable materials possess unique properties critical for advanced technologies; however, their synthesis is significantly challenging. Among the TiO 2 polymorphs, rutile TiO 2 stands out for its exceptional dielectric properties; however, its film growth typically requires high‐temperatures or lattice‐matched substrates, limiting its practical applications. This article presents a novel sacrificial layer strategy for the atomic layer deposition (ALD) of pure‐phase rutile TiO 2 films on diverse substrates, including amorphous Al 2 O 3 , HfO 2 , and ZrO 2 . This approach employs ultrathin Ru sacrificial layers to facilitate the formation of rutile TiO 2 seed layers via the in situ generation of a rutile‐matched RuO 2 lattice. At the same time, it is completely removed as volatile RuO 4 under exposure to O 3 during the ALD process. This approach eliminates the need for high‐temperature annealing and substrate restrictions, enabling low‐temperature formation of rutile TiO 2 on diverse substrates, including amorphous oxides. Comprehensive characterization reveals the structural stability of the films and their enhanced dielectric performance. Stabilizing rutile TiO 2 independently of the underlying layer opens new possibilities for its integration into memory capacitors. Furthermore, this strategy provides a versatile framework for stabilizing other metastable material phases, thereby offering opportunities for diverse applications.