High-temperature epitaxial growth of tantalum nitride thin films on MgO: structural evolution and potential for SQUID applications

The growth of superconducting tantalum nitride (TaN) thin films on magnesium oxide (MgO) substrates has been studied using pulsed laser deposition (PLD). This research investigates the influence of varying deposition parameters, including substrate temperature and ambient gas composition, on the structural, morphological, and superconducting properties of the films. X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy analyses revealed that the TaN films exhibit excellent crystallinity and smooth surface morphology, when deposited at optimal temperatures of 750 and 850 °C. The films exhibit superconducting transition temperatures (<i>T</i> _c) ranging from 5.0 to 6.3 K, depending on the stoichiometry and deposition conditions. Resistance-temperature curves further confirm the high quality of the films, as evidenced by their low residual resistivity ratios. These findings demonstrate that PLD is a suitable technique for producing high-quality TaN superconducting films.