Terahertz Spectroscopy of Ni-Ti Alloy Thin Films

ORAL

Abstract

We investigate the carrier dynamics in nickel-titanium (Ni-Ti) alloy thin films using THz transmission spectroscopy. Ni-Ti alloys have peculiar mechanical properties, in particular, shape memory effects. Electrical conductivity can be a good measure to characterize the phase transitions. We fabricated 60$\sim $80-nm Ni-Ti alloy films of various Ti concentrations (0-100{\%}). The films were deposited on Si substrates by Ar plasma sputtering. Analyzing the relative power transmission and transmitted waveforms, we obtained the alloy film resistivity of several different Ti concentrations. DC resistivity measurements were made via 4-point probe for comparison. Results show sharp changes in resistivity near the Ti fractions of 22{\%}, 44{\%}, and 62{\%} by weight. Previous studies of the Ni-Ti system have shown that the alloy undergoes a phase transition at each of these compositions.

–

Authors

  • Michael Paul

    Department of Physics, Oregon State University

  • Andrew Jameson

    Oregon State University, Department of Physics, Oregon State University, Oregon State University, Corvallis, OR 97331

  • Joe Tomaino

    Oregon State University, Department of Physics, Oregon State University

  • Josh Kevek

    Department of Physics, Oregon State University

  • Meghan Hemphill Johnston

    School of Chemical, Biological \& Environmental Engineering, Oregon State University

  • Justin Ong

    School of Chemical, Biological \& Environmental Engineering, Oregon State University

  • Milo Koretsky

    School of Chemical, Biological \& Environmental Engineering, Oregon State University

  • Ethan Minot

    Department of Physics, Oregon State University

  • Yun-Shik Lee

    Oregon State University, Department of Physics, Oregon State University, Oregon State University, Corvallis, OR 97331