Direct epitaxial growth of polar (1-x)HfO2-(x)ZrO2 ultra-thin films on Silicon

Abstract

Ultra-thin Hf1-xZrxO2 films have attracted tremendous interest owing to their Si-compatible ferroelectricity arising from polar polymorphs. While these phases have been grown on Si as polycrystalline films, epitaxial growth was only achieved on non-Si substrates. Here we report direct epitaxy of polar phases on Si using pulsed laser deposition enabled via in situ scavenging of the native a-SiOx under ballistic conditions. On Si (111), polar rhombohedral (r)-phase and bulk monoclinic (m-) phase coexist, with the volume of the former increasing with increasing Zr concentration. R-phase is stabilized in the regions with a direct connection between the substrate and the film through the compressive strain provided by an interfacial crystalline c-SiO2 layer., The film relaxes to a bulk m-phase in regions where a-SiOx regrows. On Si (100), we observe polar orthorhombic o-phase coexisting with m-phase, stabilized by inhomogeneous strains at the intersection of monoclinic domains. This work provides fundamental insight into the conditions that lead to the preferential stabilization of r-, o- and m-phases.

arXiv comment18 pages of manuscript, 7 figures

References in corpus (6)

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• A rhombohedral ferroelectric phase in epitaxially-strained Hf0.5Zr0.5O2 thin films
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• Effects of Growth Orientations and Epitaxial Strains on Phase Stability of HfO${}_2$ Thin Films
• Enhanced ferroelectricity in epitaxial Hf0.5Zr0.5O2 thin films integrated with Si(001) using SrTiO3 templates
• Epitaxial Integration on Si(001) of Ferroelectric Hf0.5Zr0.5O2 Capacitors with High Retention and Endurance

Cited by in corpus (7)

• Epitaxial Ferroelectric HfO2 Films: Growth, Properties, and Devices
• Guidelines for the stabilization of a polar rhombohedral phase in epitaxial Hf0.5Zr0.5O2 thin films
• Trilinear coupling driven ferroelectricity in HfO${}_2$
• Ferroelectricity in epitaxially strained rhombohedral ZrO2 thin films
• Critical Effect of Bottom Electrode on Ferroelectricity of Epitaxial Hf0.5Zr0.5O2 Thin Films
• Finite-size effects on the ferroelectricity in rhombohedral HfO${}_2$
• Guidelines for the optimization of hafnia-based ferroelectrics through superlattice engineering