Conductive single-phase SrMoO3 epitaxial films synthesized in pure Ar ambience via plasma-assisted radio frequency sputtering

• Published in: Science and technology of advanced materials 2024-12, Vol.25 (1), p.2378684
• Main Authors: Roy-Chowdhury, Mouli, He, Cong, Tang, Ke, Koizumi, Hiroki, Wen, Zhenchao, Thota, Subhash, Sukegawa, Hiroaki, Ohkubo, Tadakatsu, Mitani, Seiji
• Format: Article
• Language: English
• Subjects: Argon; Chemical reduction; Conductive SrMoO3; Electrical resistivity; Epitaxial growth; epitaxial thin films; Hall effect; Hydrogen; Optical, Magnetic and Electronic Device Materials; Perovskite structure; Perovskites; plasma-assisted sputtering; Radio frequency; Room temperature; Sputtering; Substrates; target-to-substrate distance; Temperature dependence; Thin films
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2024.2378684

The cubic perovskite SrMoO3 with a paramagnetic ground state and remarkably low room-temperature resistivity has been considered as a suitable candidate for the new-era oxide-based technology. However, the difficulty of preparing single-phase SrMoO3 thin films by hydrogen-free sputtering has hindered their practical use, especially due to the formation of thermodynamically favorable SrMoO4 impurity. In this work, we developed a radio frequency sputtering technology enabling the reduction reaction and achieved conductive epitaxial SrMoO3 films with pure phase from a SrMoO4 target in a hydrogen-free, pure argon environment. We demonstrated the significance of controlling the target-to-substrate distance (TSD) on the synthesis of SrMoO3; the film resistivity drastically changes from 1.46 × 105 μΩ·cm to 250 μΩ·cm by adjusting the TSD. Cross-sectional microstructural analyses demonstrated that films with the lowest resistivity, deposited for TSD = 2.5 cm, possess a single-phase SrMoO3 with an epitaxial perovskite structure. The formation mechanism of the conductive single-phase SrMoO3 films can be attributed to the plasma-assisted growth process by tuning the TSD. Temperature-dependent resistivity and Hall effect studies revealed metal-like conducting properties for low-resistive SrMoO3 films, while the high-resistive ones displayed semiconductor-like behavior. Our approach makes hydrogen-free, reliable and cost-efficient scalable deposition of SrMoO3 films possible, which may open up promising prospects for a wide range of future applications of oxide materials.