Electrical properties of the La 0.8 Sr 0.2 MnO 3 thin films on SrTiO 3 substrate by an excimer laser metal organic depos
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E3.5.1
Electrical properties of the La0.8Sr0.2MnO3 thin films on SrTiO3 substrate by an excimer laser metal organic deposition (ELMOD) process at low temperature ∗
T. Tsuchiya, T. Yoshitake, Y. Shimakawa, I. Yamaguchi, T. Manabe, T. Kumagai Y. Kubo and S. Mizuta National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Higashi Tsukuba, 305-8565, Japan Fundamental Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan ABSTRACT The electrical properties of epitaxial La0.8Sr0.2MnO3 films on a SrTiO3 (STO) substrate prepared by changing the laser fluence, the irradiation time and the film thickness using excimer laser metal organic deposition(ELMOD) at 500℃ were investigated. When the laser fluence was changed from 60 to 100mJ/cm2, the film showed a 3.9 % maximum temperature coefficient of resistance (TCR: defined as 1/R・dR/dT) which was obtained by the ArF laser irradiation at 80mJ/cm2 for 10min. At a constant fluence of 80mJ/cm2, the Tm (temperature of the maximum TCR) of the La0.8Sr0.2MnO3 films increased from 225K to near 250K with an increase in the irradiation time to 90min at which the TCR was almost 3.9%. The La0.8Sr0.2MnO3 film that showed the maximum TCR of 4.0% at 275K was obtained by the ELMOD process at 500℃using the optimum conditions (Flence:80mJ/cm2, Irradiation time: 90min, Film thickness: 80nm). INTRODUCTION Perovskite manganese oxide materials such as La1-xSrxMnO3 have recently attracted a great deal of attention due to their large temperatures coefficient of resistance (TCR) properties [1, 2, 3, 4, 5] compared with the metal or VOx system [3]. Hence, using perovskite manganese oxide materials as a IR sensor, a small-size uncooled or moderately bolometric detector with high performance could be expected to be fabricated. In most cases, however, a perovskite manganese oxide thin film is prepared by several methods at higher than 700℃, therefore, it would be difficult to prepare such films on a Si substrate. It is then necessary to develop a new low temperature process for the fabrication of a perovskite manganese oxide thin film. Recently, we developed the excimer laser MOD (ELMOD) for preparing epitaxial La0.8Sr0.2MnO3 films on an LaAlO3 (LAO) substrate by heating at 500℃ [6]. In addition, we examined the effects of the processing conditions such as the laser fluence and irradiation time and film thickness on the TCR and Tm of the La0.8Sr0.2MnO3 films on LAO substrate by ELMOD, and successfully obtained a film which showed the maximum TCR of 3.4% at 265K(Tm: temperature at which showed maximum TCR [6]. In order to improve the TCR of the films, the investigation of another important factor would be necessary. Generally speaking, the electrical properties of the ∗
Corresponding author; TEL +81-298-61-4553;
@aist.go.jp
FAX+81-298-61-4714;
E-mail; tetsuo-tsuchiya
E3.5.2
oxide films depend on the crystallinity, thus would be improved by the improving the crystallinity. From this viewpoint, the choice of the substrate materials wou
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