Sreemany, Monjoy and Bose, Ankita and Sen, Suchitra (2010) A study on structural, optical, electrical and microstructural properties of thin TiO(x) films upon thermal oxidation: Effect of substrate temperature and oxidation temperature. Physica B-Condensed Matter, 405 (1). pp. 85-93. ISSN 0921-4526

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Influences of both substrate temperature, T(s) (similar to 305, 473 K) and oxidation temperature, T(a)(similar to 623-973 K) on the structural, optical, electrical and microstructural properties of thin TiO(x) (x <= 2) films obtained by thermal oxidation of sputtered titanium thin films have been investigated. T(s) is found to be an important parameter that affects both the as deposited film morphology and phase evolution of TiO(x) films during oxidation. As deposited and oxidized films processed at T(a)similar to 623 K exist in TiO form. Formation of anatase (TiO(2)) phase takes place at T(a)similar to 723 K. As the T(a) increases above 723 K, degree of crystallinity of the film improves and rutile (TiO(2)) phase appears along with anatase phase at T(a)similar to 873 K. Further increase in the T(a) enhances the contribution of rutile phase at the expense of anatase contribution. Apparent crystallite size, L, and refractive index of the TiO(x) (x approximate to 2) films increase with T(a) but band gap energy, E(g) decreases from similar to 3.4 to 3.35eV. Scanning electron microscopic study reveals that both film densification and grain size improve with T(a). As the T(a) increases above 873 K, rutile phase contribution as well as grains of the oxidized films deposited at a lower T(s) grow at a faster rate than that of the TiO(x) films prepared at a higher T(s). Room temperature resistivity of the as deposited films is found to be dependent on T(s). Film-resistivity increases with oxidation temperature and at T(a)similar to 723 K, resistivity of the film increases drastically. Temperature coefficient of resistivity (TCR) for all the as deposited and oxidized films processed at T(a)similar to 623 K is found to be negative and lie between similar to 1.2 x 10(-3)-2.1 x 10(-3) K(-1). Thermal activation energy, E(a), of the as deposited and oxidized (T(a)similar to 623 K) TiO(x) (x approximate to 1) films is estimated to vary over the range similar to 0.015-0.027 eV. Observed change in the film electrical properties with T(a) is discussed in the light of oxygen incorporation in the TiO(x) structure. (C) 2009 Elsevier B.V. All rights reserved.

Item Type: Article
Uncontrolled Keywords: RF magnetron sputtering; TiO(x) thin films; Thermal oxidation; Scanning electron microscopy; Optical and electrical properties
Subjects: Microstructure and Characterization
Depositing User: Bidhan Chaudhuri
Date Deposited: 16 Feb 2012 10:24
Last Modified: 16 Feb 2012 10:24

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