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Nucleation of body-centered-cubic tantalum films with a thin niobium underlayer

Journal Article · · J. Vac. Sci. Technol., A; (United States)
DOI:https://doi.org/10.1116/1.574203· OSTI ID:6199270
We discuss the structural and electrical properties of high-quality Ta films prepared by ion beam sputter deposition. The Ta films grow in two different crystal structures, body-centered-cubic (bcc) or tetragonal (..beta..-Ta), depending on the substrate preparation and sputtering conditions. Ta films deposited on a thin (>0.3 nm) Nb underlayer grow in the bcc crystal structure with properties approaching those of clean bulk polycrystalline material. The bcc-Ta films have a superconducting transition temperature of 4.3 K and a low-temperature (10 K) resistivity rho--6 ..mu cap omega.. cm. Ta films deposited without a Nb underlayer on Si substrates always grow in the tetragonal (..beta..-Ta) structure. The ..beta..-Ta films do not superconduct above 1 K and have a high resistivity rho--150 ..mu cap omega.. cm. X-ray diffraction and transmission electron microscope studies of both Ta structures are presented. Both bcc-Ta and ..beta..-Ta films are deposited on room-temperature substrates. This allows either type of film to be easily patterned by standard photoresist liftoff methods.
Research Organization:
Section of Applied Physics, Yale University, New Haven, Connecticut 06520
OSTI ID:
6199270
Journal Information:
J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 5:6; ISSN JVTAD
Country of Publication:
United States
Language:
English