Synthesis of Superconductive TaN Thin Films by Reactive DC Sputtering
Por:
Nieto A., Guzmán M., Conde-Gallardo A., Contreras O.
Publicada:
1 ene 2022
Resumen:
Superconductive TaN thin films synthesized with reactive direct current (DC) sputtering were grown on silicon substrates at 600°C for 60 min with variations of the N2 gas flow ratio (RN2). The microstructure of the thin films was analyzed by transmission electron microscopy (TEM), observing a TaN polycrystalline structure constructed by stacked (200) and (111) planes. The surface morphology for almost all samples was relatively smooth with the exception of the film deposited using the highest RN2 which showed a considerably higher roughness. Chemical composition was determined by x-ray photoelectron spectroscopy (XPS) analysis. It was revealed that the thin films consist of a tantalum nitride compound with a TaNx stoichiometry ranging from 0.43 < x < 1.35. The crystallographic results of the obtained films showed that it evolved from face centered cubic (FCC) TaN structure, preferentially oriented along <111> for low RN2, to <200> preferred orientation and later to a crystal phase combination (FCC TaN and tetragonal Ta3N5) as RN2 ratios was increased. The electrical resistivity of the TaN thin films presented a clear dependence on the stoichiometry which increased considerably with the nitrogen content. All samples but the one synthesized with the highest RN2 (which presented an insulation electrical behavior) exhibited the typical stepped superconductor transition, and their superconductive transition temperature (Tc) was reduced as the preferred orientation changed from <111> to the <200> direction. This was correlated with RN2 and its effect on the crystal growth. © 2022, The Minerals, Metals & Materials Society.
Filiaciones:
Nieto A.:
CETYS Universidad, Ensenada, Mexico
Guzmán M.:
CETYS Universidad, Ensenada, Mexico
Conde-Gallardo A.:
Centro de Investigación y Estudios Avanzados, Instituto Politécnico Nacional, CINVESTAV-IPN, Mexico City, Mexico
Contreras O.:
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, CNyN-UNAM, Ensenada, Mexico
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