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Dispersion of Love waves in size-dependent substrate containing finite piezoelectric and viscoelastic layers
摘要： The dispersion properties of Love waves are utilized for the fabrication of sensor devices in the different material environments. This study involves the propagation of Love wave in a double-layered structure consisting of two finite layers of viscoelastic and piezoelectric material lying over the semi-infinite size-dependent micropolar substrate. The bottom substrate of the structure is modeled as, the material with microstructural properties. The real and damping dispersion relations are obtained analytically in closed form expression under both the cases of electrically open and short conditions. The coupling constant and characteristic length that describe the effect of the microstructure of the micropolar substrate, are studied graphically on Love wave propagation. The effects of piezoelectric layer are shown by considering two different materials of a piezoelectric layer, i.e., PZT-5H or BaTiO3, along with the internal friction and heterogeneity parameter associated with a viscoelastic layer. The numerical computation and the graphs are given for aluminium-epoxy (substrate), viscoelastic material and PZT-5H or BaTiO3 (piezoelectric layer). Some of the particular cases are derived from the study by using different relevant conditions.
关键词： Viscoelastic,Piezoelectricity,Dispersion relations,Heterogeneity,Micropolar,Love wave,Characteristic length
更新于2025-09-23 15:22:29
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Influence of Passivation Layers on Positive Gate Bias-Stress Stability of Amorphous InGaZnO Thin-Film Transistors
摘要： Passivation (PV) layers could effectively improve the positive gate bias-stress (PGBS) stability of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs), whereas the related physical mechanism remains unclear. In this study, SiO2 or Al2O3 films with different thicknesses were used to passivate the a-IGZO TFTs, making the devices more stable during PGBS tests. With the increase in PV layer thickness, the PGBS stability of a-IGZO TFTs improved due to the stronger barrier effect of the PV layers. When the PV layer thickness was larger than the characteristic length, nearly no threshold voltage shift occurred, indicating that the ambient atmosphere effect rather than the charge trapping dominated the PGBS instability of a-IGZO TFTs in this study. The SiO2 PV layers showed a better improvement effect than the Al2O3 because the former had a smaller characteristic length (~5 nm) than that of the Al2O3 PV layers (~10 nm).
关键词： thin-film transistor (TFT),positive gate bias stress (PGBS),passivation layer,characteristic length,amorphous InGaZnO (a-IGZO)
更新于2025-09-23 15:21:21
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A size-dependent micropolar-piezoelectric layered structure for the analysis of love wave
摘要： The propagation characteristics of Love wave form an essential basis for designing highly sensitive microacoustic devices for sensing applications. In this paper, the propagation of Love wave in a micropolar-piezoelectric structure is investigated with the objective of enhancing the performance of Love wave-based devices. A study has been carried out by using two sets of a piezoelectric material, i.e. PZT-5H and BaTiO3 material. The closed-form expression of the dispersion relations is derived analytically for electrically open and electrically short conditions. The effects of internal microstructures of the micropolar elastic half-space, the thickness of a piezoelectric layer, the piezoelectric constants, and the dielectric constants are illustrated graphically on the phase velocity for both the considered materials of the piezoelectric layer under electrically open and short conditions.
关键词： Piezoelectricity,Love wave,micropolar,characteristic length,dispersion relation
更新于2025-09-23 15:21:01