| 摘要 |
A surface acoustic wave device has been developed, such as a surface acoustic wave filter in which a plurality of electroacoustic interdigital electrodes are formed, as thin films made principally of aluminum, on the surface of a Li2B4O7 single crystal substrate and a surface acoustic wave resonator, in which a plurality of electroacoustic interdigital electrodes and grating reflectors for reflecting the surface acoustic wave are formed, as thin films made principally of aluminum, on the surface of a Li2B4O7 single crystal substrate. Here, a cut angle, at which the substrate is cut from the Li2B4O7 single crystal, and the propagation direction of the surface acoustic wave are so set that, when the Eulerian angle representation is (90 DEG +/- lambda , 90 DEG +/-+82, 90 DEG +/- theta ), lambda =38 DEG to 52 DEG , mu =0 DEG to 5 DEG and theta =0 DEG to 10 DEG , whereby the TCD of the surface acoustic wave device is below +/-5 ppm/ DEG C. and coupling coefficient K2 is about 1.0%, and the propagation speed suffers almost no angular dependence.
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