Direct measurement of spurious mode properties in thin film BAW resonator

K. Kokkonen, Tuomas Pensala, Johanna Meltaus, M. Kaivola

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review


    The acoustic wave fields excited in a 1.8 GHz AlN thin film bulk acoustic wave resonator are measured in detail with a heterodyne laser interferometer. The electrical response of the resonator exhibits a strong thickness resonance onto which spurious modes, caused by lateral standing plate waves, are superposed. The acoustic wave fields are measured with a heterodyne interferometer and are used to calculate dispersion diagram of the laterally propagating waves responsible for the spurious electrical responses. The dispersion diagram features a discrete eigenmode spectrum due to the finite lateral dimensions of the resonator. An equivalent circuit model for a multi-mode resonator is fitted to the mechanical resonator response extracted along a single curve in the dispersion diagram, and is used to determine properties, such as Q-values, of the individual lateral eigenmodes. Measured wave field images, extracted dispersion curves, and the eigenmode spectrum with the model fitting results are presented
    Original languageEnglish
    Title of host publicationProceedings of the IEEE Ultrasonics Symposium, IUS 2010
    PublisherIEEE Institute of Electrical and Electronic Engineers
    ISBN (Electronic)978-1-4577-0381-2
    ISBN (Print)978-1-4577-0382-9
    Publication statusPublished - 2010
    MoE publication typeA4 Article in a conference publication
    EventIEEE International Ultrasonics Symposium, IUS 2010 - San Diego, CA, United States
    Duration: 11 Oct 201014 Oct 2010


    ConferenceIEEE International Ultrasonics Symposium, IUS 2010
    Country/TerritoryUnited States
    CitySan Diego, CA


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