TY - GEN
T1 - Characterization of ZnO polycrystalline films on silica glass by the LFB ultrasonic material characterization system
AU - Kushibiki, Jun Ichi
AU - Ohashi, Yuji
AU - Arakawa, Mototaka
AU - Yoshida, Sho
AU - Kourai, Yuusuke
AU - Kondo, Takanori
AU - Fujii, Satoshi
PY - 2009
Y1 - 2009
N2 - We evaluated eleven ZnO polycrystalline films with different thicknesses fabricated on silica glass substrates by DC sputtering and RF sputtering methods using a line-focus-beam ultrasonic material characterization (LFB-UMC) system. We measured fH (product of frequency f and film thickness H) dependences of leaky surface acoustic wave (LSAW) velocities for each ZnO-film specimen. The calculated LSAW velocities decreased from 3424.3 m/s for silica glass to 2671.6 m/s for Z-cut ZnO single crystal as fH increased. The measured LSAW velocities became lower than the calculated ones: decreases of 42 m/s for the DC-ZnO film and 27 m/s for the RF-ZnO film from a calculated value of 2672.1 m/s at fH = 1680 Hz·m. These velocity decreases were related to the FWHM in c-axis orientation, resulting in decreases in elastic constant c44 E associated with ZnO polycrystalline film structure: about 6% for the DC-ZnO film and about 3% for the RF-ZnO film. We also demonstrated the capability of the system for evaluating film thickness distributions through LSAW velocity distributions. This ultrasonic method is useful for characterization of polycrystalline and epitaxial films.
AB - We evaluated eleven ZnO polycrystalline films with different thicknesses fabricated on silica glass substrates by DC sputtering and RF sputtering methods using a line-focus-beam ultrasonic material characterization (LFB-UMC) system. We measured fH (product of frequency f and film thickness H) dependences of leaky surface acoustic wave (LSAW) velocities for each ZnO-film specimen. The calculated LSAW velocities decreased from 3424.3 m/s for silica glass to 2671.6 m/s for Z-cut ZnO single crystal as fH increased. The measured LSAW velocities became lower than the calculated ones: decreases of 42 m/s for the DC-ZnO film and 27 m/s for the RF-ZnO film from a calculated value of 2672.1 m/s at fH = 1680 Hz·m. These velocity decreases were related to the FWHM in c-axis orientation, resulting in decreases in elastic constant c44 E associated with ZnO polycrystalline film structure: about 6% for the DC-ZnO film and about 3% for the RF-ZnO film. We also demonstrated the capability of the system for evaluating film thickness distributions through LSAW velocity distributions. This ultrasonic method is useful for characterization of polycrystalline and epitaxial films.
KW - DC sputtering method
KW - Layered structure
KW - Leaky surface acoustic wave velocity
KW - LFB ultrasonic material characterization system
KW - RF magnetron sputtering method
KW - Velocity distribution
KW - Zno polycrystalline films
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UR - http://www.scopus.com/inward/citedby.url?scp=77952800713&partnerID=8YFLogxK
U2 - 10.1109/ULTSYM.2009.5441455
DO - 10.1109/ULTSYM.2009.5441455
M3 - Conference contribution
AN - SCOPUS:77952800713
SN - 9781424443895
T3 - Proceedings - IEEE Ultrasonics Symposium
SP - 1575
EP - 1578
BT - 2009 IEEE International Ultrasonics Symposium and Short Courses, IUS 2009
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2009 IEEE International Ultrasonics Symposium, IUS 2009
Y2 - 20 September 2009 through 23 September 2009
ER -