Philippe Pigeat

Packageless AlN/ZnO/Si Structure for SAW Devices Applications

The possibility to perform a packageless structure for acoustic wave sensors applications based on AlN/interdigital transducer/ZnO/Si structure was investigated. The effect of thicknesses of AlN and ZnO thin films on structure performance was simulated by 2-D finite element method. Theoretical predictions were confirmed by in-situ measurements of frequency, insertion loss, and thickness during deposition of AlN layer on ZnO/Si.

Packageless temperature sensor based on AlN/IDT/ZnO/Silicon layered structure

The possibility to generate simultaneously Surface Acoustic Wave (SAW) and Waveguiding layer acoustic wave (WLAW) in layered structures AlN/ZnO/Silicon was investigated. A delay line operating at 525 MHz was tested versus temperature in air and in contact with liquid. Experimental characterizations were also supported by modeling using the commercial software (COMSOL Multiphysics). The full delay line was simulated and liquid modeled by an additional layer on the top of AlN film.

Ultraviolet optical excitation of near infrared emission of Yb-doped crystalline aluminum oxynitride thin films

Yb3+ ions hold promises for high power emission in the near infrared (NIR). Yet, relevant matrices, comprising mediators to excite Yb3+, have to be found and the optical mechanisms have to be studied in detail. The purpose of this study is to report on the optical excitation and emission mechanisms of NIR photoluminescence (PL) of Yb-doped crystalline aluminum oxynitride thin films prepared at room temperature using reactive magnetron sputtering. Crystal structure and chemical composition are analyzed by transmission electron microscope and Rutherford backscattering spectrometry, respectively. Photoluminescence spectroscopies are used to investigate the excitation and emission mechanisms. NIR emission at 985 nm is obtained under indirect optical excitation using the 325 nm line of a He-Cd laser, the excitation mechanism is explored by photoluminescence excitation measurement (PLE), and the fine structure of the emitted energy levels is investigated by performing PL measurements at low temperature (LTPL). PLE shows that the host defects play the role of mediators to transfer the excitation energy to Yb ions. This offers different possibilities for the development of multiple excitation channels for Yb3+. Stark splitting of the energy levels of the 2F5/2 and 2F7/2 transitions is evidenced using LTPL in the 78 to 295 K range. Electronic transitions are ascribed to experimental emission lines based on good agreement with theoretical values. Moreover, the activation energies for PL thermal quenching are determined and correspond to the energy difference between highest energy quenched lines and thermally activated “hotlines.”Yb3+ ions hold promises for high power emission in the near infrared (NIR). Yet, relevant matrices, comprising mediators to excite Yb3+, have to be found and the optical mechanisms have to be studied in detail. The purpose of this study is to report on the optical excitation and emission mechanisms of NIR photoluminescence (PL) of Yb-doped crystalline aluminum oxynitride thin films prepared at room temperature using reactive magnetron sputtering. Crystal structure and chemical composition are analyzed by transmission electron microscope and Rutherford backscattering spectrometry, respectively. Photoluminescence spectroscopies are used to investigate the excitation and emission mechanisms. NIR emission at 985 nm is obtained under indirect optical excitation using the 325 nm line of a He-Cd laser, the excitation mechanism is explored by photoluminescence excitation measurement (PLE), and the fine structure of the emitted energy levels is investigated by performing PL measurements at low temperature (LTPL). ...

AlN/ZnO/LiNbO 3 packageless structure as a low-profile sensor for on-body applications

This paper describes the potential of the AlN/ZnO/LiNbO3 structure for packageless surface acoustic wave sensors. This structure, based on the waveguiding acoustic wave principle, is studied numerically and experimentally.

Theoretical and experimental study of ScAlN/Sapphire structure based SAW sensor

Several SAW devices based on Sco.1Alo.9N/Sapphire bilayer structures were fabricated using various wavelengths and film thicknesses. The acoustic velocity, electromechanical coupling coefficient and temperature coefficient of frequency (TCF) of each device was then measured and the results were compared with calculations using several sets of elastic, piezoelectric and dielectric constants available in the literature. We have shown that the accuracy of available constants is not enough to permit a reliable optimization and design of SAW devices for signal processing and sensors applications.