Browsing by Author "Serhane, Rafik"

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    Design Optimization Of Saw Temperature Sensor Based One Port Resonator Using Fem Simulation
    (Oum-El-Bouaghi University, 2021) Belkhelfa, Nabila; Serhane, Rafik
    Surface acoustic wave (SAW) sensors fabricated on high-temperature piezoelectric substrates have attracted considerable attention due to their properties. Because it is important to model the SAW devices accurately, a simulation study of Rayleigh wave properties based on a stacked Al/AlN/Si (100) device was achieved, in this paper. Evolution curves of acoustic phase velocity, reflectivity and electromechanical coupling efficiency; for different aluminum (Al) electrode patterns and different piezoelectric aluminum nitride (AlN) layer thicknesses, were elaborated by 2D FEM COMSOL simulations. Added to that, the simulated acoustic mode shapes and the harmonic admittance of the device were represented. The best (AlN) layer thickness and electrode width were 1.5µm and 1µm respectively; they were deduced from the obtained SAW characteristics curves. After that, we used the deduced parameters for the conception of one port resonator temperature sensor working at a frequency of 1.166GHz. Using an elaborated theoretical temperature model coupled to FEM model, frequency shift induced by the SAW device temperature variation was evaluated from the return losses (S11) parameter curves in a range of (-25°C to 200°C). The relative frequency change was about 0.17% and the sensor’s sensitivity was evaluated at 8.53ppm/°C.
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    The Heterostructure Zno/al/sio2/si Fabrication For Piezoelectric Saw And Baw Transducers And Sensors
    (Oum-El-Bouaghi University, 2017) Serhane, Rafik; Hadj-Larbi, F.; Lafane, S.; Abdelli-Messaci, S.; Boutkedjirt, T.
    Zinc oxide (ZnO) thin films were deposited by pulsed laser deposition technique for making ZnO/Al/SiO2/Si Bulk and Surface Acoustic Wave (BAW and SAW) transducers. The aim is to improve the piezoelectric properties of the ZnO films, which are strongly linked to their texture and microstructure. ZnO films with a wurtzite structure were deposited on the Al electrode layer, at different substrate temperatures, within the 100-500°C range. The characterization by X-ray diffraction showed that the deposited Al electrode was (111) oriented and that the ZnO film has a c-axis (002) preferential orientation. The scanning electron microscopy of the ZnO films on Al/SiO2/Si substrate showed an evidence of compact grains with a honeycomb-like structure on surface and a columnar structure on cross-section appeared after a sequential transition of amorphous to non-oriented to crystalline phase. The results indicated that the optimum substrate temperature is of 300°C and the electrical input impedance measurement on the Al/ZnO/Al BAW structure showed a piezoelectric response, where the fundamental resonance mode was located at 160 MHz, with an electromechanical coupling coefficient Keff2 equal to 3.2%. The best piezoelectric response is obtained at the fourth (4th) thickness mode vibration, located at the frequency of 636.3 MHz and having Keff2 of 9.10%.