Presentation Information
[16a-WL2_101-5]Novel complex nitride PrTaN2 thin film grown by molecular beam epitaxy
〇Kosuke Takiguchi1, Yoshiharu Krockenberger1, Yoshitaka Taniyasu1, Hideki Yamamoto1 (1.NTT BRL)
Keywords:
complex nitride,molecular beam epitaxy,thin film
Ternary nitrides composed of lanthanides and sixth-period transition metals such as Ta, W, and Re have attracted considerable interest because they can crystallize in diverse structures, including perovskite, Ruddlesden–Popper, and infinite-layer types, which are potentially associated with functional properties such as high-temperature superconductivity and ferroelectricity. However, their synthesis is highly challenging due to the requirement of strong nitridation and the extremely high melting points of the constituent transition metals.In this study, we report the thin-film synthesis, crystal growth, and structural characterization of a novel ternary nitride, PrTaN2, grown by molecular beam epitaxy. Pr and Ta were supplied to the substrate by electron-beam evaporation, with their fluxes precisely controlled in real time using electron-impact emission spectroscopy. Nitrogen radicals were employed as the nitrogen source. The effects of nitrogen flow rate, radical source power, and substrate temperature on crystal growth were systematically investigated.X-ray diffraction measurements of films grown on YAlO3(001) substrates revealed clear (001), (002), and (004) diffraction peaks of PrTaN2, indicating excellent out-of-plane orientation without detectable impurity phases. Additional reflections from multiple crystallographic planes were observed, allowing the crystal structure to be identified as orthorhombic with lattice parameters a = 3.97 Å, b = 3.38 Å, and c = 4.02 Å. Scanning transmission electron microscopy, together with reflection conditions and ionic valence considerations, strongly supports the assignment of the composition to PrTaN2. The successful discovery of this new compound via thin-film synthesis demonstrates a promising pathway for expanding the materials space of complex nitrides.