[19a-Z15-1~10] 6.4 Thin films and New materials

▲ [19a-Z15-1] Fabrication of fluorine-ion conducting LaF₃ epitaxial thin films assisted by CF₄ reactive gas

〇(DC)Xin DAI¹, Ryota Shimizu^1,2, Taro Hitosugi¹ (1.Tokyo Tech., 2.JST-PRESTO)

Keywords:Fluoride thin film, Reactive magnetron sputtering, Fluorine ionic conductor

Metal fluorides (e.g., MgF₂, LaF₃) exhibit unique properties ranging from high broadband optical transmittance to high F-ion conduction. These properties open up novel optoelectronic and electrochemical applications. For the understanding of the intrinsic properties of metal fluorides, it is essential to fabricate high-quality epitaxial thin films. For the fabrication of metal fluoride thin films using magnetron sputtering, reactive gases such as CF₄ and SF₆ are commonly used to compensate many fluorine deficiencies . In these cases, the impurities from the reactive gases are inevitable, deteriorating the intrinsic physical properties. Here, we show the fabrication of F-ion conducting LaF₃ epitaxial thin films using CF₄ gas as a model case. We found that the addition of H₂ to CF₄ during the sputtering successfully suppress the incorporation of carbon impurities into LaF₃ thin films.