Title :
Theoretical studies on LiNbO3/sapphire layered structure with SiO2 over layer for zero TCD SAW device applications
Author :
Tomar, Monika ; Gupta, Vinay ; Sreenivas, K.
Author_Institution :
Dept. of Phys. & Astrophys., Delhi Univ., India
Abstract :
Surface acoustic wave (SAW) propagation characteristics of c-axis oriented LiNbO3 thin films on epitaxially matched sapphire substrate have been calculated theoretically. C-axis oriented LiNbO3 films on sapphire substrates exhibit a low coupling coefficient (less than 1.5% for LiNbO3 thickness varying between 0 to 0.3λ) and a high positive TCD (82-96 ppm/°C) for LiNbO3 thickness varying between 0 to 0.5λ. Introduction of a nonpiezoelectric SiO2 over-layer with a negative TCD is found to compensate for the high positive TCD of the layered structure yielding a zero TCD and an enhanced coupling coefficient. The thickness of SiO2 and LiNbO3 layers have been optimized, and a high coupling coefficient of 3.94% with zero TCD has been achieved for a SiO2/LiNbO3/sapphire layered structure with 0.29λ thick LiNbO3 layer, and 0.3λ thick SiO 2 over-layer
Keywords :
lithium compounds; piezoelectric materials; sapphire; silicon compounds; surface acoustic waves; Al2O3; LiNbO3 thickness; LiNbO3/sapphire layered structure; SAW propagation characteristics; SiO2 over layer; SiO2-LiNbO3-Al2O3; SiO2/LiNbO3/sapphire layered structure; c-axis oriented LiNbO3 thin film; coupling coefficient; high positive TCD; nonpiezoelectric over-layer; sapphire substrate; temperature coefficient of delay; zero TCD SAW device application; Acoustic waves; Frequency; Piezoelectric films; Pulsed laser deposition; Sputtering; Substrates; Surface acoustic wave devices; Surface acoustic waves; Temperature; Transistors;
Conference_Titel :
Ultrasonics Symposium, 2001 IEEE
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-7177-1
DOI :
10.1109/ULTSYM.2001.991623
