Development of Brillouin scattering technique to characterize minute spatial distribution of elastic properties of thin films.

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In order to realize the non-destructive and non-contact Brillouin scattering measurement technique for the characterization of elastic property distribution in thin films, following studies were performed by the support of this program.The microscopic system for Raman scattering was applied to this optical system and realized the measurement with the spatial resolution of 10 micron meter. The introduction of Reflection Induced theta A (RIGA) scattering also enabled the simultaneous measurements of the light scatterings from hypersonic longitudinal and shear phonons. The degradation of sample surfaces by the laser irradiation was not observed.In addition to the improvement of signal to noise ratio at the photon counting part, we have tried to amplify the scattering light intensity making use of the induced hypersonic waves in the sample. Especially, we made effort to amplify the very weak light scattering from thermal shear phonons. For this purpose, we have fabricated the uniaxially oriented ZnO polycrystallites films on the sample by magnetron sputtering. We have then succeeded in fabricating the film whose resonant frequency is around several hundreds MHz. Making use of the higher resonance mode of this film, shear waves in the GHz range was successfully emitted to the samples. These coherent hypersonic waves were observed as a very intensive Brillouin scattering peak in the measured data, showing the asymmetric spectra. The intensive peak shortened the necessary time to observe the scattering in the sample and improved the signal to noise ratio and the measurement precision.For the automatic measurement of this microscopic Brilllouin scattering, the automatic position control system of the sample holder was constructed. In addition, the attached CCD in the microscopic system can give us the information of optical microscopic image of the measured area.