The epitaxial growth of Zr-doped CeO2 (CZO) films by chemical solution deposition (CSD) on single crystal substrates such as Al2O3, SrTiO3 and Y2O3-stabilized ZrO2 (YSZ) and their use as buffer layers for Fe(Se,Te) film growth are reported. The growth of 30 nm thin CZO films is mostly dominated by dewetting issues, leading to highly incomplete substrate coverage due to the strong tendency of CZO grains to agglomerate. This effect is less severe on YSZ substrate and, in addition, can be fully controlled by setting the deposition temperature at 950 °C and operating under Ar-H2 reducing atmosphere. These conditions promote the growth of epitaxial and compact CZO films on YSZ, showing a flat surface morphology with root-mean-square roughness around 2.5 nm. Preliminary results on Fe(Se,Te) film deposited by pulsed laser deposition on CZO-buffered YSZ are reported. Although good epitaxial growth is achieved on CZO buffer layer, Fe(Se,Te) films exhibit poor superconducting properties. On the other hand, Fe(Se,Te) films show excellent properties when a seed layer is used, exhibiting a sharp superconducting transition at about 17 K and a critical current density exceeding 1 MA cm-2 at 4.2 K in self field. The main role of the seed layer, consisting of a non-superconducting Fe(Se,Te) film, is to favour the crystal and chemical matching between buffer layer and film, allowing for the growth of high-quality superconducting Fe(Se,Te) at deposition temperature as low as 200 °C. In perspective of applications, this result is a significant step towards process simplification and cost reduction of Fe(Se,Te)-based coated conductor technology development, being the first demonstration of superconducting Fe(Se,Te) films grown on CSD buffer layer.
Vannozzi, A., Prili, S., Sylva, G., Masi, A., Armenio, A.A., Mancini, A., et al. (2020). Epitaxial Zr-doped CeO2films by chemical solution deposition as buffer layers for Fe(Se,Te) film growth. SUPERCONDUCTOR SCIENCE & TECHNOLOGY, 33(8), 084004 [10.1088/1361-6668/ab9aa7].