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We investigate the performance of aluminum nitride (AlN)-based solidly mounted resonators (SMR) made with iridium (Ir) electrodes for applications in WCDMA filters. Ir/AlN/Ir stacks are grown on top of insulating Bragg mirrors composed of alternate lambda/4 layers of silicon oxycarbide (SiOC) and silicon nitride (Si3N4). We have developed the technological processes for the fabrication of filters...
In this work we analyze the vibrational behavior of microresonators (cantilevers and bridges) actuated with piezoelectric aluminum nitride (AlN) films, to investigate the suitability of these devices as mass sensors. The resonators of different geometries consisted of a freestanding unimorph structure made up of a metal/AlN/metal piezoelectric stack supported by a Si3N4 structural layer. The out-of-plane...
We present picosecond ultrasonic characterizations on e-beam evaporated Ir thin films and on AlN films deposited by pulsed DC reactive sputtering on Ir. Picosecond ultrasonics is an optical technique which uses ultrashort laser pulses to generate and detect very short acoustic pulses. We first investigate the properties of the Ir films by measuring samples of various thicknesses and deposition parameters...
We report the growth of highly c-axis-textured aluminum nitride (AlN) films deposited by sputtering on evaporated iridium (Ir) layers. The crystal quality of the polycrystalline AlN films is analyzed as a function of the deposition conditions of the Ir electrode, which include the substrate temperature and the use of various seed layers, such as AlN, Ti and Ti/Mo. The influence of the sputter parameters...
In this paper, we analyze the vibrational spectra of mechanical resonators actuated piezoelectrically with aluminum nitride (AlN) films. The microresonators consist in bimorph cantilevers with different lengths containing a piezoelectric metal/AlN/metal stack supported by a silicon nitride structural layer. The thicknesses of both the AlN and Si3N4 layers are varied between 0.3 mum and 1 mum to study...
We analyse the mechanical response of a doubly-clamped microbridge actuated piezoelectrically using sputtered AlN, working first as an actuator and then as a resonator. The quasi-static response of the microbridge under DC electrical excitation is measured. Out-of-plane displacements as high as 0.22 mum/V are obtained, which provides an actuation response suitable for RF switching applications. On...
Aluminum nitride (AlN) thin films of different crystal qualities have been evaluated by Fourier transform infrared spectrophotometry (FTIR) in the transmittance and reflectance modes. The positions and intensities of the longitudinal optical (LO) and transverse optical (TO) modes in the IR spectra have been correlated with the morphological properties of the films, assessed by X-ray diffraction (XRD)...
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