Investigation on the effect of metal layer on the piezoelectric properties of ScAlN thin film

Abstract

In this study the structure of ScAlN/metal/LiNbO3 will be used to improve the piezoelectric properties The lithium niobate substrate has a high electromechanical coupling system (k2) and good piezoelectric properties and the scandium aluminum nitride film has also greatly improved the piezoelectric coefficient which also improve the k2 The addition of the right metal layer can effectively improve the piezoelectric properties In addition the addition of the metal layer will result in different wave speeds which can keep energy between the regions reduces the insertion loss and increases k2 Different metal layers of aluminum titanium chromium and molybdenum are deposited on the lithium niobate substrate by electron gun evaporation and then the scandium aluminum nitride film is deposited on the metal layer by reactive magnetron sputtering In order to improve the piezoelectric properties of scandium aluminum nitride films the effects of different metals and their thickness on the film properties and piezoelectric properties are discussed When the scandium aluminum nitride film grows on the 60 nm titanium metal layer the sample reaches the highest d33 which is an increase of 97% At this time the piezoelectric film has the maximum tensile stress and the (002) plane tilt angle which may cause larger crystal plane distortion and lattice asymmetry so that the piezoelectric coefficient is significantly improved indicating that this structure is beneficial to the application of the surface acoustic wave device of the multilayer structure

Date of Award	2020
Original language	English
Supervisor	Jow-Lay Huang (Supervisor)