Controlling CeO₂-(001) Film Surface Instability during Thermochemical Processing

Cerium oxide (CeO2) is a highly valuable material for various technological applications, particularly as a buffer layer in thin film deposition and epitaxial growth. In thin film technology, buffer layers such as CeO2 are crucial to facilitate high-quality film growth on incompatible substrates, reducing lattice mismatch and minimizing defects during epitaxial growth. This is especially significant in high-performance superconducting devices known as coated conductors (CCs) that use CeO2 buffer layers to ensure optimal performance. The quality of the buffer layer is vital, requiring (001)-oriented growth, layer continuity, and low roughness. This study explores (001)-oriented, CeO2-based buffer layer growth via polymer-assisted deposition (PAD), assessing various methods to promote the exposure of the polar, highly unstable (001) surface, through a wide comparative analysis of different compositions and processing parameters backed with a theoretical explanation of the results. We show that processes such as thermal grooving/surface reconstruction can be controlled to obtain oriented, epitaxial films with low roughness values (<1 nm) and no porosity, suitable for their use as templates for the deposition of a superconducting layer.