| Budget Amount *help |
¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
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| Research Abstract |
The purpose of this project is to establish the accurate evaluation technique of oxygen contents in oxide thin films using non-Rutherford elastic resonance scattering (NRERS). First, it was examined how parameters of the samples affect the NRERS signal intensity by measuring NRERS of samples whose oxygen content is known. It was confirmed that the NRERS signal intensity of an amorphous and a single crystal substrates with the identical composition of Si02 was the same, suggesting that there is no crystallinity effect in the NRERS cross section. The conductivity effect onto NRERS signals was also examined in reduced rutile-type TiO_2 (001) or perovskite-type SrTiO_3 (001) crystal substrates. Again, there observed no systematic relation between conductivity (or caner concentration) and NRERS intensity, though the signal intensity scattered among the samples. In total, I conclude that the parameters such as crystallinity and conductivity do not affect the NRERS signal intensity.
Next, the actual oxygen contents of strongly-correlated thin film samples, such as perovskite-type manganites Lai_<1-x>SrxMnO_<3-y> (LSMO) and ruthenates SrRuO_<3-y>, (SRO), were evaluated by means of NRERS and were compared with their electro-magnetic properties. The oxygen contents of LSMO films do not show a monotonous increase but do show a U-type dependency along the oxygen partial pressure during deposition. Thus it was revealed that the efficiency of oxygen incorporation into the films during pulsed laser deposition is worse in some oxygen pressure. On the other hand, the oxygen contents of Ar-annealed SRO films decreased as the annealing temperature increased, as far as the crystal structure is maintained. Also, the conductive property gradually changed from metallic to insulating. These are the first quantitative results that the electric-magnetic properties of oxide thin films change according to their oxygen contents.
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