High-Temperature Epitaxial Growth of Tantalum Nitride Thin Films on MgO Substrates: 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 examines how varying deposition parameters, substrate temperature, and ambient gas composition affect the structural, morphological, and superconducting properties of the films. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Atomic Force Microscope (AFM) and Transmission electron microscopy (TEM) results show that the TaN films possess excellent crystallinity and smooth surface morphology, with an optimal deposition temperature of 850 °C. The films exhibit superconducting transition temperatures (T _C ) ranging from 5.0 K to 9.3 K, depending on the stoichiometry and deposition conditions. Electrical resistivity measurements further confirm the high quality of the films, reflected by their low residual resistivity ratios. These results indicate that PLD is a suitable method for producing high-quality TaN superconducting films.

This study emphasizes the role of deposition parameters in tuning the superconducting properties, particularly for applications in superconducting electronics and quantum computing. Additionally, these films are potentially used in susceptible devices like Superconducting Quantum Interference Devices (SQUIDs), with further improvement possible through optimizing stoichiometry and reducing oxygen impurities.