title: Measurements of the bulk, C-axis electromechanical coupling constant as a function of AlN film quality.
abstract: Piezoelectric thin film AlN has great potential for on-chip devices such as thin-film resonator (TFR)-based bandpass filters. The AlN electromechanical coupling constant, K(2), is an important material parameter that determines the maximum possible bandwidth for bandpass filters. Using a previously published extraction technique, the bulk c-axis electromechanical coupling constant was measured as a function of the AlN X-ray diffraction rocking curve [full width at half maximum (FWHM)]. For FWHM values of less than approximately 4 degrees , K (2) saturates at approximately 6.5%, equivalent to the value for epitaxial AlN. For FWHM values >4 degrees , K(2) gradually decreases to approximately 2.5% at a FWHM of 7.5 degrees . These results indicate that the maximum possible bandwidth for TFR-based bandpass filters using polycrystalline AlN is approximately 80 MHz and that, for 60-MHz bandwidth PCS applications, an AlN film quality of >5.5 degrees FWHM is required.
authors.forename: R S
authors.initials: RS
authors.lastname: Naik
authors.forename: J J
authors.initials: JJ
authors.lastname: Lutsky
authors.forename: R
authors.initials: R
authors.lastname: Reif
authors.forename: C G
authors.initials: CG
authors.lastname: Sodini
authors.forename: A
authors.initials: A
authors.lastname: Becker
authors.forename: L
authors.initials: L
authors.lastname: Fetter
authors.forename: H
authors.initials: H
authors.lastname: Huggins
authors.forename: R
authors.initials: R
authors.lastname: Miller
authors.forename: J
authors.initials: J
authors.lastname: Pastalan
authors.forename: G
authors.initials: G
authors.lastname: Rittenhouse
authors.forename: Y H
authors.initials: YH
authors.lastname: Wong