Torné Sandoval, Wilmar J.

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    Fabricación y caracterización de películas de dióxido de vanadio (VO2) depositadas por sputtering con corriente continua pulsada
    (2011) Torné Sandoval, Wilmar J.; Fernández, Félix E.; College of Arts and Science - Science; Marrero, Pablo J.; Ramos, Rafael A.; Department of Physics; Santana Morant, Dámaris
    Thin films of vanadium dioxide were grown on glass and sapphire substrates by the pulsed-dc sputtering technique. This compound is of great interest because it exhibits a semiconductor (monoclinic phase) to metal (tetragonal phase) transition at a temperature of ~ 68ºC, along with an abrupt change in its resistivity. Vanadium is a polyvalent metal, and therefore a variety of vanadium oxides exist, including mixed phases, which can be produced during film fabrication. In order to obtain the correct composition and crystal structure required the exploration of a range of conditions for deposition parameters, since there are no previous reports of VO2 growth by pulsed-dc sputtering. The crystal structure of the samples was analyzed by x-ray diffraction (XRD) and their electrical properties were characterized measuring resistance as a function of temperature. The monoclinic VO2 phase was obtained with a 90 sccm argon flux, total sputtering pressure of 6.03mTorr, oxygen partial pressure of ~ 0.33 mTorr, gun power of 300 W, 150 kHz frequency, inverse time of 2.5 μsec and substrate temperature of 550ºC. Films grown on sapphire exhibited better crystal quality and their resistance change during the transition was greater than three orders of magnitude, with a narrow (3º) hysteresis curve, while those grown on glass exhibited a resistance change of over two orders of magnitude and a broad (12º) hysteresis curve.