J0402-1-6 波長可変ピコ秒超音波法の開発と酸化物薄膜の減衰評価法の提案([J0402-1]超音波計測・解析法の新展開(1))

概要

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Thin-film mechanical resonators are promising for high frequency bandpass filters. Amorphous oxide thin films are expected to be important candidates because they are free from grain scattering loss. However, it has been difficult to characterize their acoustic properties, especially attenuation, which is a key parameter for designing a high-Q resonator. Here, we present a novel methodology for evaluating ultrasonic attenuation of amorphous oxide thin films deposited on silicon substrate at very high frequencies between 200 and 300 GHz. This method uses the high sensitivity of the refractive index of light in silicon near to the wavelength near 400 nm. Detecting Brillouin oscillations from silicon substrate, which is caused by the transmitted acoustic wave, we can evaluate the frequency dependence of the attenuation coefficient in the thin film through an inverse calculation.
2010-09-04