Title :
The effects of ZnO films on surface acoustic wave properties of modified lead titanate ceramic substrates
Author :
Chu, Sheng-Yuan ; Chen, Te-Yi ; Water, Walter
Author_Institution :
Dept. of Electr. Eng., Nat. Cheng Kung Univ., Tainan, Taiwan
Abstract :
Poly-crystal zinc oxide (ZnO) films with c-axis [002] orientation have been successfully grown on the strontium (Sr) modified lead titanate ceramic substrates with different Sr dopants by r.f. magnetron sputtering technique. Highly oriented ZnO films with c-axis normal to the substrates can be obtained under a total pressure of 10 mTorr containing 50% argon and 50% oxygen and r.f. power of 70 W for 3 hours. Crystalline structures of the films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The phase velocity, electromechanical coupling coefficient arid temperature coefficient of frequency of surface acoustic wave (SAW) devices with ZnO/IDT/PT (IDT, inter-digital transducer; PT, PbTiO/sub 3/ ceramics) structure were investigated. The devices with ZnO/IDT/PT structure shows that the ZnO film effectively raise the electromechanical coupling coefficient (k/sup 2/) from 3.8% to 9.9% of the device with the concentrations of Sr dopants of 0.15. It also improves the temperature coefficient of frequency of SAW devices.
Keywords :
II-VI semiconductors; X-ray diffraction; atomic force microscopy; crystal structure; interdigital transducers; lead compounds; piezoceramics; scanning electron microscopy; semiconductor thin films; sputter deposition; surface acoustic waves; wide band gap semiconductors; zinc compounds; 3 hour; 70 W; AFM; PbTiO/sub 3/:Sr; SAW devices; SEM; X-ray diffraction; XRD; ZnO-PbTiO/sub 3/; atomic force microscopy; crystalline structures; electromechanical coupling coefficient; interdigital transducer; polycrystal zinc oxide films; rf magnetron sputtering technique; scanning electron microscopy; strontium modified lead titanate ceramic substrates; surface acoustic wave properties; Acoustic waves; Atomic force microscopy; Ceramics; Scanning electron microscopy; Strontium; Substrates; Surface acoustic waves; Temperature; Titanium compounds; Zinc oxide;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2005.1563275
