AVS 51st International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeA

Paper TF-WeA4
Analysis on Thermal Properties of Tin-doped Indium Oxide Films by Picosecond Thermoreflectance Measurement

Wednesday, November 17, 2004, 3:00 pm, Room 303C

Session: Transparent Conducting Oxides
Presenter: T. Yagi, Aoyama Gakuin University, Japan
Authors: T. Yagi, Aoyama Gakuin University, Japan
K. Tamano, Aoyama Gakuin University, Japan
Y. Sato, Aoyama Gakuin University, Japan
N. Taketoshi, National Metrology Institute of Japan
T. Baba, National Metrology Institute of Japan
Y. Shigesato, Aoyama Gakuin University, Japan
Correspondent: Click to Email
First time attempt of observation of thermal diffusion across tin doped indium oxide (ITO) thin films perpendicular to the film plane has been carried out using a picosecond thermoreflectance measurement@footnote 1@. ITO films sandwiched by molybdenum (Mo) films were prepared on fused silica substrate by rf magnetron sputtering using ITO and Mo multi-targets. Such Mo/ITO/Mo layered structure was fabricated without exposure to the atmosphere between each deposition. The Mo films with thickness of 70 nm are necessary because the wavelength of pulse laser used in this study is 780 nm at which wavelength ITO is transparent. The ITO films with different thickness of 30, 50 and 70 nm were prepared as the intermediate layer in order to estimate thermal resistance at the interface between Mo/ITO. The resistivity, carrier density and Hall mobility of the ITO film was 4.2e-4 ohm cm, 3.5e20 cm@super -3@ and 35 cm@super 2@/Vsec, respectively. The interface between the Mo films and the fused silica substrate was irradiated by picosecond laser pulse (2 ps). Heat generated by the pump laser pulse diffuses toward the top Mo surface across the three-layered films. Then the temperature changes at the Mo film surface, which was probed by reflectivity of another picosecond laser pulse. The thermal diffusion time increased with the increase in the thickness of the ITO layers. The thermal diffusion coefficient of the ITO films and thermal resistance at ITO/Mo were found to be 3e-6 m@super 2@/s and 1e-8 mK/W, respectively. This research was supported in part by the New Energy and Industrial Technology Development Organization (NEDO) in Japan. @FootnoteText@ 1: N. Taketoshi, T. Baba, E. Schaub, A. Ono: Rev. Sci. Instrum., 74, (2003), pp. 5226-5230.