基于钽酸锂晶片的热释电探测器敏感元研制

发布时间：2018-04-24 03:04

本文选题：热释电探测器 + 钽酸锂　；参考：《电子科技大学》2017年硕士论文

【摘要】：基于钽酸锂的热释电探测器由于其具有能在常温下工作、光谱响应范围宽,热释电系数大、价格便宜和器件制备简单等特点,广泛用于非接触式温度测量设备、运动检测器和气体分析仪中。而钽酸锂敏感元是其核心,它的优劣直接决定着器件的性能。本论文主要对钽酸锂敏感元的制备进行了较为系统的研究,研究的具体内容包括热释电探测器理论分析、钽酸锂晶体抛磨工艺、红外吸收层的制备与表征以及热释电探测器性能的测试。首先,分析了热释电探测器的原理和基本性能参数,接着采用了机械研磨法和化学机械抛光法分别对钽酸锂晶片进行了减薄与抛光,分别研究了研磨液浓度、主轴转速、压力对减薄速率的影响和温度、氧化剂浓度、溶液的pH值对化学机械抛光速率的影响,并优化了减薄抛光工艺参数,对晶片表面形貌作了表征。然后,采用了高压静电喷涂法制备油墨-炭黑红外吸收层,并进行了吸收层的表征和吸收率的测试。研究了电压和喷涂高度对吸收层质量的影响,当电压16kV,喷涂距离为3cm时,喷涂量为5μl时吸收层表面较为均匀平整,厚度为2μm左右,粗糙度为500nm。通过红外吸收率的测试,发现油墨-炭黑吸收层对近红外光的吸收率非常高,达到了90%以上。最后,对热释电探测器进行了封装与性能测试,测量了不同粗糙度的钽酸锂晶片的介电常数和和介电损耗,对不同钽酸锂厚度、不同入射功率、不同表面粗糙度、不同调制频率下的电压响应进行了测试,并通过热学仿真分析响应电压波形,同时测试比较了不同表面粗糙度敏感元、不同频率下的噪声。随着钽酸锂晶片厚度的减小响应率逐渐增大,当厚度达到50μm时,器件响应率达到了4.62×103V/W。器件的响应随着入射光的功率成正比,在低频时探测器的电压响应随着频率的升高而增大,在一定频率范围内探测器的电压响应与频率无关,在高频时,器件的电压响应随着频率升高逐渐减小。敏感元表面经过抛光后的器件噪声明显减小,粗糙度为Ra 50nm的敏感元器件噪声低到2μV/Hz,通过计算可得探测器的等效噪声光功率为4.3×10-10W/Hz1/2,比探测率为3.3×108cm·Hz1/2/W,符合高性能热释电探测器对敏感元的要求。
[Abstract]:The pyroelectric detector based on lithium tantalate is widely used in non-contact temperature measurement equipment, motion detector and gas analyzer because of its ability to work at normal temperature, wide spectrum response range, high pyroelectric coefficient, cheap price and simple device preparation, and the lithium tantalate sensitive element is the core of the thermoluminescence detector. In this paper, the preparation of the lithium tantalate sensitive element is systematically studied in this paper, including the theoretical analysis of pyroelectric detector, the polishing process of lithium tantalate crystal, the preparation and characterization of the infrared absorption layer and the test of the performance of the pyroelectric detector. First, the principle of pyroelectric detector is analyzed. The basic performance parameters, then the thinning and polishing of lithium tantalate wafers were carried out by mechanical grinding and chemical mechanical polishing. The influence of grinding fluid concentration, spindle speed, pressure on thinning rate and temperature, concentration of oxidant, pH value of solution on the mechanical polishing rate of chemical mechanical polishing were studied respectively, and the thinning polishing was optimized. The surface morphology of the wafer was characterized by the process parameters. Then, the ink carbon black infrared absorption layer was prepared by high voltage electrostatic spraying, and the absorption layer was characterized and the absorption rate was tested. The influence of the voltage and spraying height on the absorption layer quality was studied. When the voltage 16kV, spraying distance was 3cm, the coating surface was 5 U L. It is more uniform and smooth, the thickness is about 2 mu m, and the roughness is 500nm. through the infrared absorption test. It is found that the absorption rate of the ink carbon black absorption layer is very high and up to 90%. Finally, the package and performance test of the pyroelectric detector are carried out, and the dielectric constant and the dielectric constant of the lithium tantalate wafer with different roughness are measured and the dielectric constant is measured. The electric loss is tested on the voltage response of different lithium tantalate thickness, different incident power, different surface roughness and different modulation frequency, and the response voltage waveform is analyzed by thermal simulation. At the same time, the noise of different surface roughness sensitive element and different frequency is tested and compared. With the thickness of lithium tantalate wafer decreasing, the response rate is reduced. When the thickness reaches 50 m, the response rate of the device reaches 4.62 x 103V/W., and the response of the device is proportional to the power of the incident light. The voltage response of the detector increases with the increase of frequency at low frequency. The voltage response of the detector is not related to the frequency in a certain frequency range. At high frequency, the voltage response of the device is along with the frequency. The increase gradually decreases. The noise of the device on the surface of the sensitive element decreases obviously. The noise of the sensitive component with the roughness of Ra 50nm is low to 2 V/Hz, and the equivalent noise power of the detector is 4.3 x 10-10W/Hz1/2 by calculation, and the specific detection rate is 3.3 x 108CM. Hz1/2/W, which is in line with the requirements of the high performance pyroelectric detector to the sensitive element.

【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN215

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