Composite Resonator Structure Research Articles

10.1007/s11487-008-3014-y

Acoustic loss in a composite longitudinal-wave resonator structure operating in the microwave band are studied. The resonator structure contains a rather thick sapphire plate coated with a piezoelectric film with electrodes. It is shown that, in a wide frequency band, attenuation is determined by interaction with acoustic phonons. The role of diffraction loss is discussed. Scattering of acoustic waves by asperities of reflecting surfaces is considered, and the contribution of scattered acoustic waves to the total loss is estimated.

Calculation of acoustic energy trapping in resonators based on isotropic and nanoceramic materials

The problem of acoustic energy trapping in a microwave resonator structure operating on the basis of acoustic waves and containing a relatively thick nanoceramic plate, which has a piezoelectric film with electrodes on its surface, is solved. For a composite resonator structure made on the basis of isotropic substrates and nanoceramics, formulas are derived that allow one to choose the thicknesses of its layers to obtain a high Q factor at a desired frequency.

The loss mechanism in a composite acoustic microwave resonator based on a sapphire single crystal

Acoustic loss in a composite longitudinal-wave resonator structure operating in the microwave band are studied. The resonator structure contains a rather thick sapphire plate coated with a piezoelectric film with electrodes. It is shown that, in a wide frequency band, attenuation is determined by interaction with acoustic phonons. The role of diffraction loss is discussed. Scattering of acoustic waves by asperities of reflecting surfaces is considered, and the contribution of scattered acoustic waves to the total loss is estimated.

An exact solution to the problem of trapping of oscillation energy in microwave-band acoustic resonators based on cubic crystals

An exact solution is obtained to the problem of the oscillation spectrum in a microwave-band composite resonator structure that can work on longitudinal and transverse acoustic waves and contains a comparatively thick cubic-crystal plate and a piezoelectric film with electrodes deposited on the plate. The problem is solved for the resonator operating at high-order harmonics of the fundamental frequency of the plate in the case when the ratio between the thicknesses of the resonator and other layers of the structure is sufficiently large. The derived formulas can be used to analyze the possibility of achieving a high Q factor of a composite resonator structure at a desired frequency.

Property characterization of AlN thin films in composite resonator structure

AlN thin films with c-axis orientation have been investigated for fabricating thin film bulk acoustic wave resonators in the past few years. Characterization of thin film material properties including density, elastic modulus, and piezoelectric coefficient is essential in processing study and for predicting the performance of the acoustic devices. In this paper, we present our results on the fabrication of highly c-axis oriented AlN thin films on Pt∕Ti∕Si (100) substrates by dc reactive magnetron sputtering method. The crystalline structure and the surface morphology of AlN films are characterized by x-ray diffraction and scanning electron microscopy. The effective piezoelectric coefficient d33eff of the AlN films was measured by a laser interferometer method and the piezoelectric coefficient d33 was estimated. A recently developed resonance spectrum method is applied to characterize the electromechanical properties of AlN thin films based on the input electrical impedance equation derived by one-dimensional transmission line theory for composite resonators. Using the experimental impedance spectrum data, the density and elastic constant of the piezoelectric AlN thin film in the four-layer composite resonator structure are evaluated. The calculated results reveal that the piezoelectric coefficient d33, density, and velocity of the c-axis oriented AlN thin film are 4.19pm∕V, 3187.3kg∕m3, and 10631m∕s, respectively.

Acoustic characterization of AlN films using a High Overtone Bulk acoustic wave resonator

Using the composite resonator with additional thick AlN film with the FWHM of rocking curve of 2.53° under investigation, the bulk acoustic wave attenuation constant and sound velocity along c-axis were directly measured. The method of High Overtone Bulk acoustic wave Resonator (HBAR) spectroscopy based on frequency, measurements of the positions of the resonator peculiarities of phase and amplitude of electromagnetic wave reflection coefficient from composite resonator structure was applied. The method provides attenuation and velocity measurement in a wide frequency band, using the same sample. For the measurements, standard and modified HBAR spectroscopy based on the analysis of only parallel resonance properties of composite resonator structures were used.

Split frequencies in planar axisymmetric gyroelectric resonators

Axisymmetric gyroelectric disk, ring, and composite resonator structures have been characterized for both InSb and GaAs semiconductors at 77 K. The calculations assume that these materials can be represented by the tensor permittivity derived from the Drude model of cyclotron motion in a plasma. Resonance and loss regions are identified and the sensitivity of normal mode splitting and onset frequencies to material and geometrical variables are graphed and tabulated. The information is presented in terms of signal frequency and the bias field to permit a direct comparison with results from ferrimagnetic structures. Semiconductor calculations show two extraordinary wave resonances and predict excellent symmetrical wide-band normal mode splitting. Field plots for the semiconductor disk and ring are included to explain coupled mode behaviour between modes in different bias regions.

The method of lines for the hybrid analysis of multilayered cylindrical resonator structures

A very powerful numerical model based on the method of lines (MoL) is developed for the hybrid analysis of composite multilayered cylindrical dielectric resonator structures. These structures are composed of a number of coaxial rings which are arbitrarily layered in the axial direction, the resonant frequencies, as well as quality factors caused by radiation or dielectric loss and the corresponding field distributions of all resonant modes can be determined with the described algorithm. The theory is verified in case of the conical dielectric resonator and a comparison of our numerical results with those of other authors shows excellent consistency.