a-plane Mg{sub x}Zn{sub 1-x}O films deposited on r-sapphire and its surface acoustic wave characteristics
- Department of Electrical and Computer Engineering, Rutgers, State University of New Jersey, 94 Brett Road, Piscataway, New Jersey 08854 (United States)
Piezoelectric zinc oxide (ZnO) and its ternary alloy magnesium zinc oxide (Mg{sub x}Zn{sub 1-x}O) films are deposited on r-plane (0112) sapphire (Al{sub 2}O{sub 3}) substrates using the hybrid deposition technology by combining metal-organic chemical vapor deposition (MOCVD) and sputtering. An ultra-thin ZnO buffer is first grown on r-Al{sub 2}O{sub 3} by MOCVD technique, followed by a thick piezoelectric Mg{sub x}Zn{sub 1-x}O (0{<=}x{<=}0.3) film deposited using RF sputtering. The sputtering targets are made by mixing ZnO and MgO powders in appropriate composition ratio, and nickel oxide (NiO) powder (2 wt%) is added as the compensation dopant to achieve piezoelectricity. The as-deposited Mg{sub x}Zn{sub 1-x}O films have a-plane (1120) orientation in a wurtzite crystal structure. The crystallinity of the films is further improved by annealing at 600-700 deg. C in oxygen ambient. It is found that a ZnO thin buffer layer and post-deposition annealing process significantly improve the film's piezoelectric properties. The c-axis of the Mg{sub x}Zn{sub 1-x}O film lies in the plane of the substrate, resulting in the in-plane anisotropy of the piezoelectric properties. The surface acoustic wave (SAW) devices are fabricated on the piezoelectric a-plane Mg{sub x}Zn{sub 1-x}O films. The Rayleigh-type waves propagate parallel to the c-axis while the Love-type waves propagate perpendicular to the c-axis.The SAW characteristics in the Mg{sub x}Zn{sub 1-x}O/r-Al{sub 2}O{sub 3} structure are tailored by changing the Mg mole composition in Mg{sub x}Zn{sub 1-x}O. Simulation results of the SAW properties are found to be in close agreement with the experimental results.
- OSTI ID:
- 20979503
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 25, Issue 4; Other Information: DOI: 10.1116/1.2748801; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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