TY - JOUR
T1 - Analysis of SAW properties in ZnO/Al xGa 1-xN/c-Al 2O 3 structures
AU - Chen, Ying
AU - Emanetoglu, Nuri William
AU - Saraf, Gaurav
AU - Wu, Pan
AU - Lu, Yicheng
AU - Parekh, Aniruddh
AU - Merai, Vinod
AU - Udovich, Eric
AU - Lu, Dong
AU - Lee, Dong S.
AU - Armour, Eric A.
AU - Pophristic, Milan
N1 - Funding Information:
Manuscript received July 23, 2004; accepted November 16, 2004. This work has been supported by the National Science Foundation under the grants ECS-0088549 and ECS-0224166, and the New Jersey Commission on Science and Technology with the Research Excellence Center grant “Multimode Wireless Sensor (MUSE)”.
PY - 2005/7
Y1 - 2005/7
N2 - Piezoelectric thin films on high acoustic velocity nonpiezoelectric substrates, such as ZnO, AlN, or GaN deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films are deposited on Al xGa 1-xN/c-Al 2O 3 (0 ≤ x ≤ 1) substrates using the radio frequency (RF) sputtering technique. In comparison with a single Al xGa 1-xN layer deposited on c-Al 2O 3 with the same total film thickness, a ZnO/Al xGa 1-xN/c- Al 2O 3 multilayer structure provides several advantages, including higher order wave modes with higher velocity and larger electromechanical coupling coefficient (K 2). The surface acoustic wave (SAW) velocities and coupling coefficients of the ZnO/Al xGa 1-xN/c-Al 2O 3 structure are tailored as a function of the Al mole percentage in Al xGa 1-xN films, and as a function of the ZnO (h 1) to Al xGa 1-xN (h 2) thickness ratio. It is found that a wide thickness-frequency product (hf) region in which coupling is close to its maximum value, K max 2, can be obtained. The K max 2 of the second order wave mode (h 1 = h 2) is estimated to be 4.3% for ZnO/GaN/cAl 2O 3, and 3.8% for ZnO/AlN/c-Al 2O 3. The bandwidth of second and third order wave modes, in which the coupling coefficient is within ±0.3% of K max 2, is calculated to be 820 hf for ZnO/GaN/c-Al 2O 3, and 3620 hf for ZnO/AlN/cAl 2O 3. Thus, the hf region in which the coupling coefficient is close to the maximum value broadens with increasing Al content, while K max 2 decreases slightly. When the thickness ratio of AlN to ZnO increases, the K max 2 and hf bandwidth of the second and third higher wave modes increases. The SAW test devices are fabricated and tested. The theoretical and experimental results of velocity dispersion in the ZnO/Al xGa 1-xN/c-Al 2O 3 structures are found to be well matched.
AB - Piezoelectric thin films on high acoustic velocity nonpiezoelectric substrates, such as ZnO, AlN, or GaN deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films are deposited on Al xGa 1-xN/c-Al 2O 3 (0 ≤ x ≤ 1) substrates using the radio frequency (RF) sputtering technique. In comparison with a single Al xGa 1-xN layer deposited on c-Al 2O 3 with the same total film thickness, a ZnO/Al xGa 1-xN/c- Al 2O 3 multilayer structure provides several advantages, including higher order wave modes with higher velocity and larger electromechanical coupling coefficient (K 2). The surface acoustic wave (SAW) velocities and coupling coefficients of the ZnO/Al xGa 1-xN/c-Al 2O 3 structure are tailored as a function of the Al mole percentage in Al xGa 1-xN films, and as a function of the ZnO (h 1) to Al xGa 1-xN (h 2) thickness ratio. It is found that a wide thickness-frequency product (hf) region in which coupling is close to its maximum value, K max 2, can be obtained. The K max 2 of the second order wave mode (h 1 = h 2) is estimated to be 4.3% for ZnO/GaN/cAl 2O 3, and 3.8% for ZnO/AlN/c-Al 2O 3. The bandwidth of second and third order wave modes, in which the coupling coefficient is within ±0.3% of K max 2, is calculated to be 820 hf for ZnO/GaN/c-Al 2O 3, and 3620 hf for ZnO/AlN/cAl 2O 3. Thus, the hf region in which the coupling coefficient is close to the maximum value broadens with increasing Al content, while K max 2 decreases slightly. When the thickness ratio of AlN to ZnO increases, the K max 2 and hf bandwidth of the second and third higher wave modes increases. The SAW test devices are fabricated and tested. The theoretical and experimental results of velocity dispersion in the ZnO/Al xGa 1-xN/c-Al 2O 3 structures are found to be well matched.
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U2 - 10.1109/TUFFC.2005.1504002
DO - 10.1109/TUFFC.2005.1504002
M3 - Article
C2 - 16212255
AN - SCOPUS:24944489373
VL - 52
SP - 1161
EP - 1168
JO - IRE Transactions on Ultrasonic Engineering
JF - IRE Transactions on Ultrasonic Engineering
SN - 0885-3010
IS - 7
ER -