P1G-5 Ion Beam Sputter-Deposited ZnO Thin Film for Broadband Shear Wave Excitation in the GHz Range

In-plane and out-of-plane oriented (112macr0) ZnO thin films are attractive for shear wave excitation in the GHz range. It is proposed here that highly oriented and submicron-thick (112macr0) ZnO thin films can be fabricated using ion beam sputter-deposition system with grazing incidence to the substrate surface. This (112macr0) texture formation 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 [101macr0] or [112macr0] direction). Full-width-at-half-maximum (FWHM) values of the phi-scan and psi-scan profile curves of the (112macr2) X-ray diffraction poles were measured to be 5deg and 28deg, respectively. A shear-wave transducer with a 0.9-mum-thick film exhibited an untuned 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.