TY - GEN
T1 - The resonance characteristics of solidly mounted resonators with 1/2 λ and 1/4 λ configurations
AU - Wei, Ching Liang
AU - Chen, Ying Chung
AU - Cheng, Chien Chuan
AU - Wang, Chih Ming
AU - Kao, Kuo Sheng
AU - Hsieh, Po-Tsung
PY - 2008/11/13
Y1 - 2008/11/13
N2 - The solidly mounted resonator (SMR) is composed of a piezoelectric AlN thin film sandwiched between two electrodes and a Bragg reflector consisting of alternating high and low acoustic impedance layers of quarter-wavelength thickness. According to the different arrangements of high and low acoustic impedance layers, SMR devices form two resonance modes, i.e. 1/2 λ and 1/4 λ mode configurations. The purpose of this study is to compare the resonance characteristics of these two configurations. The thickness of the piezoelectric layer for 1/4 λ, mode configuration is set equal to a half of that for 1/2 λ mode configuration. Therefore, the piezoelectric thin film for 1/2 λ mode configuration exhibits better crystallization owing to its film thickness. It leads to a high coupling coefficient, k2, and a wide bandwidth if piezoelectric thin film is fabricated with good crystalline characteristics. As to 1/4 λ mode configuration with moderate film thickness, it has a better surface smoothness and a lower stress resulting in a slight scattering of the acoustic wave. As a result, the SMR device with 1/4 λ mode configuration leads to a high quality factor. The return loss outside passband is obviously close to zero for the 1/4 λ mode configuration.
AB - The solidly mounted resonator (SMR) is composed of a piezoelectric AlN thin film sandwiched between two electrodes and a Bragg reflector consisting of alternating high and low acoustic impedance layers of quarter-wavelength thickness. According to the different arrangements of high and low acoustic impedance layers, SMR devices form two resonance modes, i.e. 1/2 λ and 1/4 λ mode configurations. The purpose of this study is to compare the resonance characteristics of these two configurations. The thickness of the piezoelectric layer for 1/4 λ, mode configuration is set equal to a half of that for 1/2 λ mode configuration. Therefore, the piezoelectric thin film for 1/2 λ mode configuration exhibits better crystallization owing to its film thickness. It leads to a high coupling coefficient, k2, and a wide bandwidth if piezoelectric thin film is fabricated with good crystalline characteristics. As to 1/4 λ mode configuration with moderate film thickness, it has a better surface smoothness and a lower stress resulting in a slight scattering of the acoustic wave. As a result, the SMR device with 1/4 λ mode configuration leads to a high quality factor. The return loss outside passband is obviously close to zero for the 1/4 λ mode configuration.
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U2 - 10.1109/FREQ.2008.4622991
DO - 10.1109/FREQ.2008.4622991
M3 - Conference contribution
AN - SCOPUS:55649094900
SN - 9781424417957
T3 - 2008 IEEE International Frequency Control Symposium, FCS
SP - 209
EP - 212
BT - 2008 IEEE International Frequency Control Symposium, FCS
T2 - 2008 IEEE International Frequency Control Symposium, FCS
Y2 - 19 May 2008 through 21 May 2008
ER -