ZnO薄膜超声换能器的研制及其声光器件研究

发布时间：2018-04-28 04:42

本文选题：光纤声光器件 + ZnO薄膜超声换能器　；参考：《华中科技大学》2016年博士论文

【摘要】：近年来,集成化、微型化是声光器件的发展必然趋势,而用于声光器件中的压电薄膜体声波换能器,正成为国内外研究的热点。采用压电薄膜制备的体声波换能器与传统声光器件中的超声换能器相比,具有超声波频率高、插入损耗小、超声波频率带宽大、Q值高和易于声光晶体集成等优点,在传感探测、光电通信、超声医学检验等领域,应用前景十分广阔。ZnO是六方纤锌矿结构的多功能半导体材料,由于具有良好的压电性能,在声体波谐振器、声表面波器件和压电传感器等产品中得到极为广泛应用,所以它是制备压电薄膜的首选材料。ZnO薄膜超声换能器是光纤声光器件的核心元件,同时由于ZnO薄膜超声换能器技术复杂性以及对光纤声光器件性能良好的需求,本文工作主要集中在ZnO薄膜超声换能器的全面理论分析和数值建模,优化振动模式和抑制横模泛频,确定现有磁控溅射仪器的的最佳工艺参数,通过对衬底Si上的ZnO薄膜超声换能器进行XRD和SEM微观测试,结果显示ZnO薄膜c轴取向一致,横模泛频得到很好的抑制,最后进行基于ZnO薄膜超声换能器的光纤声光器件的声光效应性能测试,测试结果显示光纤声光器件的衍射效率符合理论分析。本论文的主要研究内容包括：在体声波理论的基础上,引入力学中夹层板模型,增加ZnO中间层的压电剪切应力的影响,避免了传统模型Mason模型中忽略电极厚度、电极阻抗等物理参数的缺点,将电磁波多次反射共振理论用来分析超声波在ZnO薄膜超声换能器传输,获得厚度(纵波)模式的频率色散方程,获得更为普适的换能器模型,模型方程的简化结果和MBVD模型一致,验证了模型的正确性。在普适性模型的基础上,采用多物理场耦合软件Comsol对ZnO薄膜超声换能器进行模拟仿真分析,获得压电晶体材料,电极材料、厚度和面积物理参数,对薄膜换能器工作频率和带宽的影响,为如何获得满足声光效应的ZnO超声换能器的物理参数选型,提供明确的指导方向。为了获得优质的ZnO薄膜,研究了磁控溅射设备的工艺控制参数对ZnO薄膜成膜质量的影响,通过一系列ZnO薄膜样品的XRD表征分析获得了制备高质量的ZnO薄膜的工艺参数。在衬底温度为400℃C,Ar与O2比例40：20,气氛压强：4.0 Pa,溅射功率：200W中制备出了性能优良的Si衬底高质量(002)晶向的ZnO薄膜,AFM表面形貌分析晶粒直径在3.42nm。在Tiersten方程基础上,研究了圆形和环形电极横模泛频产生的机理,引入电磁场模式理论解释了环形电极横模泛频比圆形电减少的原因,获得和软圆柱体声波散射共振理论相同的结论,并通过内外径比控制环形电极的ZnO薄膜超声换能器的基频,然后通过外差激光干涉仪和网络分析仪分析比较了两种换能器的横模泛频寄生的振动图样和电阻抗曲线,验证激励方程分析结果,为横模泛频抑制提供了理论基础。采用Matlab数值分析软件,从声光耦合方程入手,模拟仿真了光纤声光器件的衍射效率,将制备的ZnO薄膜超声换能器用于光纤声光器件测试,然后进行声光效应实验测试,分析了衍射率随入射光波长和超声波频率的变化,得到和理论仿真一致的结果。总之,本论文的研究从理论和实验上对ZnO薄膜超声换能器进行全新的理论数值建模、性能测试、泛频抑制和基于ZnO薄膜超声换能器的声光器件测试分析,这为类似压电超声薄膜器件的制备和模式优化提供理论基础,而且对基于薄膜声光器件的性能研发也有一定的指导作用。
[Abstract]:In recent years, integration and miniaturization are the inevitable trend of acousto-optic devices, and the piezoelectric thin film acoustic transducer used in acousto optic devices is becoming a hot spot at home and abroad. With the advantages of high frequency bandwidth, high Q value and easy acousto-optic crystal integration,.ZnO is a multi-functional semiconductor material in six square wurtzite structure in the fields of sensing detection, photoelectric communication and ultrasonic medical inspection, and so on. Due to the good piezoelectric properties, it is produced in acoustic wave resonator, surface wave device and piezoelectric sensor. It is the most widely used product, so it is the first choice material for the preparation of piezoelectric thin film.ZnO thin film ultrasonic transducer is the core component of the optical fiber acoustooptic device. At the same time, because of the complexity of the ZnO thin film ultrasonic transducer and the good performance of the optical fiber optic device, this paper mainly concentrates on the overall ZnO film ultrasonic transducer. Theoretical analysis and numerical modeling, optimize the vibration mode and suppress the transverse mode pan frequency, determine the best process parameters of the existing magnetron sputtering instrument. Through the XRD and SEM micro testing of the ZnO film ultrasonic transducer on the substrate Si, the results show that the c axis of the ZnO film is the same orientation, the transverse mode pan is well suppressed. Finally, the ZnO film is carried out based on the ZnO film. The test results show that the diffraction efficiency of the optical fiber acousto-optic device accords with the theoretical analysis. The main research contents of this paper include: on the basis of the theory of sonic wave, the sandwich plate model in mechanics is introduced to increase the influence of the piezoelectric shear stress in the middle layer of ZnO, so as to avoid the tradition. In the model Mason model, the defects of the electrode thickness and the electrode impedance are ignored. The multiple reflection resonance theory of electromagnetic wave is used to analyze the transmission of ultrasonic wave in the ZnO film ultrasonic transducer and obtain the frequency dispersion equation of the thickness (P-wave) mode. The more universal model of the transducer is obtained. The simplified result of the model equation is consistent with the MBVD model. The correctness of the model is verified. On the basis of the universal model, the multi physical field coupling software Comsol is used to simulate and simulate the ZnO thin film ultrasonic transducer. The influence of the piezoelectric crystal material, the electrode material, the thickness and area physical parameters, the working frequency and the bandwidth of the film transducer, and how to obtain the Z to satisfy the acoustooptic effect are obtained. The physical parameters selection of nO ultrasonic transducer provides a clear direction. In order to obtain high quality ZnO film, the influence of the process control parameters of the magnetron sputtering equipment on the film forming quality of the ZnO film is studied. The process parameters of the high quality ZnO film are obtained by the XRD characterization analysis of a series of ZnO film samples. The substrate temperature is 4. 00 C C, Ar and O2 40:20, the atmosphere pressure: 4 Pa, sputtering power: the high quality (002) crystalline ZnO film of the Si substrate with excellent performance is prepared. The AFM surface morphology analysis grain diameter is on the Tiersten equation based on 3.42nm.. The mechanism of the universal frequency generation of the circular and ring electrode transverse modes is studied, and the theoretical solution of the electromagnetic field mode is introduced. The reason for the reduction of the circular frequency ratio of circular electrode to circular electrode is explained, and the same conclusion is obtained with the theory of acoustic scattering resonance of the soft cylinder, and the fundamental frequency of the ZnO film ultrasonic transducer is controlled by the ratio of inner and outer diameter to the annular electrode. Then the transverse mode pan parasitism of the two transducers is analyzed and compared by the heterodyne laser interferometer and the network analyzer. The vibration pattern and the impedance curve are used to verify the result of the excitation equation analysis, which provides the theoretical basis for the horizontal mode pan suppression. The Matlab numerical analysis software is used to simulate the diffraction efficiency of the optical fiber acoustooptic device from the acoustooptic coupling equation. The ZnO film ultrasonic transducer is used to test the optical fiber acoustooptic device, and then the sound is carried out. The variation of diffraction rate with the incident light wavelength and ultrasonic frequency is analyzed, and the results are consistent with the theoretical simulation. In a word, the theoretical and Experimental Research on the theoretical and experimental new theoretical numerical modeling, performance testing, pan frequency suppression and sound and light based on the ZnO thin film ultrasonic transducer are carried out in theory and experiment. The test and analysis of the device provides a theoretical basis for the fabrication and mode optimization of the piezoelectric ultrasonic thin film devices, and also has some guidance for the performance research and development of the thin film acoustooptic devices.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB552

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