Highly Oriented ZnO Thin Films Deposited by Grazing Ion-Beam Sputtering: Application to Acoustic Shear Wave Excitation in the GHz Range

概要

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In-plane and out-of-plane oriented ($11\bar{2}0$) ZnO thin films are attractive for acoustic shear wave excitation in the GHz range. In this study it is proposed that highly oriented and submicron-thick ($11\bar{2}0$) ZnO thin films can be fabricated using an ion beam sputter-deposition system with grazing incidence to the substrate surface. The formation of the ($11\bar{2}0$) texture cannot only be attributed to the well-known ion-channeling effect or to the self-shadowing effect since the ion beam incidence direction in the system does not correspond to the ion-channeling direction of the ZnO film (the [$10\bar{1}0$] or [$11\bar{2}0$] direction). The full width at half-maximum (FWHM) values of the $\phi$- and $\psi$-scan profile curves of the ($11\bar{2}2$) X-ray diffraction poles were measured to be 5 and 28°, respectively. A shear-wave transducer with a 0.9-μm-thick film exhibited a one-way conversion loss of less than 20 dB at 1–2 GHz and a 3 dB fractional bandwidth of 100%, without any longitudinal wave excitation.
Japan Society of Applied Physicsの論文
2007-12-25