【摘 要】
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In this paper, a solidly mounted resonator (SMR) was designed with tetrahedral amorphous carbon (ta-C) as the high acoustic impedance material of Bragg reflector to improve the electricity and acousti
【机 构】
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Center of Composite Materials, Harbin Institute of Technology, Harbin 150001, China
【出 处】
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第十一届全国表面工程大会暨第八届全国青年表面工程学术会议
论文部分内容阅读
In this paper, a solidly mounted resonator (SMR) was designed with tetrahedral amorphous carbon (ta-C) as the high acoustic impedance material of Bragg reflector to improve the electricity and acoustic quality. We investigated the effect of the Bragg reflector on the properties of SMR, as well as the influence of the sp3 fraction in ta-C and the thickness deviation of high/low acoustic impedance layers on quality factor Q and effective electromechanical coupling factor keff by MathCAD. It has been showed that the quality of SMR was improved with the increase of alternating layers in Bragg reflectors and ta-C presented more advantages as high acoustic impedance material comparing with other choices such as AlN, Si3N4 and CVD diamond. With higher sp3 fraction in ta-C, saturated Q factor can be reached with fewer layers. There should be only six layers (three pairs) in order to get an excellent Q factor when the sp3 fraction in ta-C was 80%. The thickness deviation of high/low acoustic impedance layers closer to the piezoelectric stack had greater effect on Q factor. Therefore, ta-C is a good choice of high acoustic impedance material in the design of SMR with high frequency and low loss to improve the quality. The sp3 fraction should be large and the thickness of alternating layers close to the bottom electrode should be precise.
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