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微结构气敏传感器敏感薄膜制备方法的研究 总被引:5,自引:1,他引:4
随着微结构气敏传感器的出现,金属氧化物半导体薄膜因具有灵敏度高、热质量小、批量制备一致性好等特点受到日益广泛的重视,本比较了在微结构气敏传感器中三种方法制备的SnO2敏感薄膜的结构和气敏响应特性。结果表明,用液涎生长和热氧化技术制备Sn2薄膜虽然能采用Lift-off技术成形,但由于膜中晶粒结构和Sn/O比不合适使得它的气敏响应特性很差;室温混合气氛(Ar/O2比为8:2)下射频溅射SnO2靶然 相似文献
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微结构气敏传感器敏感薄膜制备方法的研究 总被引:2,自引:0,他引:2
随着微结构气敏传感器的出现 ,金属氧化物半导体薄膜因具有灵敏度高、热质量小、批量制备一致性好等特点受到日益广泛的重视。本文比较了在微结构气敏传感器中三种方法制备的SnO2 敏感薄膜的结构和气敏响应特性。结果表明 ,用液涎生长和热氧化技术制备的SnO2 薄膜灵敏度高、稳定性好 ,但这种方法与lift off技术不兼容 ;室温直流溅射Sn然后热氧化方法制备的SnO2 薄膜虽然能采用lift off技术成形 ,但由于膜中晶粒结构和Sn/O比不合适使得它的气敏响应特性很差 ;室温混合气氛 (Ar/O2 比为 8∶2 )下射频溅射SnO2 靶然后退火制备的SnO2 薄膜 ,不仅对有机分子十分灵敏 ,而且与微电子工艺相容。室温射频溅射是制备微结构气敏传感器敏感薄膜较理想的方法 相似文献
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γ-Al2O3基纳米陶瓷气敏元件稳定性研究 总被引:2,自引:0,他引:2
报道对采用纳米粉料制作的γ-Al2O3基气敏元件的稳定性的研究结果。分别采用纳米粉料和微米级粉料制备了γ-Al2O3基气敏元件,该气敏元件对碳氢化合物还原性气体敏感;连续17个月测定了这些气敏元件对甲烷的气敏特性;通过XPS等技术分别在3个阶段对这两种元件的表面化学元素含量进行了表征。结果表明,元件失效的原因之一是由于在气敏反应过程中由于部分反应产物在表面沉积造成表面活性位减少,并导致吸附能力下降所致;而元件失效或不稳定与使用过程中元件表面有沉积物有关。通过以上研究工作,找出了利用纳米粉料制备气敏元件失效快和长期工作稳定性差的部分原因,为该类材料的进一步发展提供实验依据。 相似文献
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掺杂对金属半导体氧化物气敏性能影响的研究 总被引:5,自引:2,他引:3
综述了金属氧化物半导体气敏元件的掺杂技术,探讨了掺杂作用的机理,列举了对最典型半导体气敏元件的掺杂以及掺杂对气敏元件灵敏度和选择性的影响作用。 相似文献
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针对香皂容易失水的问题做了香皂收缩包装的研究.研究了不同材料对香皂包装失水性的影响,以及不同形状香皂的裹包与收缩包装对其失水性的影响.经实验分析,用POF薄膜收缩包装后再放入纸盒中的包装方法阻湿效果最好. 相似文献
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M. G. Boguslavskii 《Measurement Techniques》1963,6(10):829-832
Conclusions The above semiconductor thermometer with a special transducer is convenient for measuring the temperature of flat, spherical, and fashioned outer and inner surfaces.The special transducer provides temperature measurements lasting not more than 10 sec. The error in measuring temperature does not exceed ±0.3°.The above technique for determining corrections of temperature deviations from the normal of the article and the measuring instrument by means of a semiconductor thermometer and special graphs raises the accuracy of measurement and productivity in manufacturing precision articles on metal-working machines, and reduces the percentage of rejects due to inaccurate measurements.The above technique and instrument can be used under workshop conditions at the bench, in the Technical Control Division (OTK), inspection and test points, in factory test laboratories, and in GKLs for measuring equipment of the State Committee of Standards, Measures, and Measuring Instruments of the USSR. 相似文献
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Rahani EK Kundu T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(10):2213-2221
Transient ultrasonic waves in a fluid medium generated by a flat circular and a point-focused transducer of finite size are modeled by the distributed point source method (DPSM). DPSM is a Green's-function-based semi-analytical mesh-free technique which is modified here to incorporate the transient loading from a finite-sized acoustic transducer. Conventional DPSM solves acoustic problems in steady-state frequency domain. Here, DPSM is extended to the time domain without the fast Fourier transform (FFT) but using the Green's function in the time domain. This modified method is denoted t-DPSM. Harmonic point sources of DPSM are replaced by time-dependent point sources in t-DPSM. Generated t-DPSM results are compared with the finite element (FE) results for both focused and flat circular transducers. The developed method is used to solve the transient problem of wave scattering by an air bubble in a fluid as the bubble is moved horizontally or vertically from the focal point of the focused transducer. The received energy signal is compared for different eccentricities. 相似文献
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Sensing a buried resonant object by single-channel time reversal 总被引:1,自引:0,他引:1
Waters Z.J. Dzikowicz B.R. Holt R.G. Roy R.A. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(7):1429-1441
Scaled laboratory experiments are conducted to assess the efficacy of iterative, single-channel time reversal for enhancement of monostatic returns from resonant spheres in the free field and buried in a sediment phantom. Experiments are performed in a water tank using a broad-band piston transducer operating between 0.4 and 1.5 MHz and calibrated using free surface reflections. Solid and hollow metallic spheres, 6.35 mm in diameter, are buried in a consolidation of 128-μm-mean- diameter spherical glass beads. The procedure consists of exciting the target object with a broadband pulse, sampling the return using a finite time window, reversing the signal in time, and using this reversed signal as the source waveform for the next interrogation. Results indicate that the spectrum of the returns rapidly converges to the dominant mode in the backscattering response of the target. Signal-to-noise enhancement of the target echo is demonstrated for a target at several burial depths. Images generated by scanning the transducer over the location of multiple buried targets demonstrate the ability of the technique to distinguish between targets of differing type and to yield an enhancement of different modes within the response of a single target as a function of transducer position and processing bandwidth. 相似文献
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L. Satyanarayan Anish Kumar T. Jayakumar C. V. Krishnamurthy Krishnan Balasubramaniam Baldev Raj 《Journal of Nondestructive Evaluation》2009,28(3-4):111-124
New techniques developed using the array transducer, to image and size the bottom-surface and near-through-wall crack-like defects in thick carbon steel components are discussed. Three studies are reported here including (a) Optimal beam steering angle for focused and unfocused inspection using phased array method for bottom-surface crack sizing. (b) A front wall correction algorithm for sizing of near-through-wall crack-like defects. (c) A small aperture technique for sizing of near-through-wall crack-like defects. A Finite Difference Time Domain (FDTD) based simulation was used to study and verify the experimental observations. The application of time domain scheme relative arrival time technique (RATT), to measure the size of the near-through wall crack-like defects for the leak before break (LBB) criterion, was also investigated and found to be insufficient. A conventional SAFT algorithm was used for improving the sizing using the small aperture technique. 相似文献
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半导体制冷片因其体积小、制冷速度快的优点在冷藏链运输领域具有很强的应用潜力。为测试半导体制冷箱的制冷效率,本文搭建了制冷储藏箱性能测试实验台,对应用两片TEC1-12706型及TEC1-12712型半导体制冷片的制冷储藏箱的工作性能进行实验研究。实验中分别在储藏箱中加入2 000 m L冰块开始实验及应用1 500 mL冰块与3 kg食材及3瓶500 mL矿泉水的组合开始实验,两次实验中同时改变热端散热方式及冷端风扇吹风方式。结果表明:对于同型号半导体制冷片,水冷方式时制冷效果更好,但持久性不强;同型号半导体制冷片冷端风扇下吹方式与侧吹方式相比气流组织更好。当容积为0. 1 m^3的储藏箱面向冷藏需求时,可应用两片采取热端风冷方式的TEC1-12706型半导体制冷片,此时10 h内箱体中心温度最大约为6℃,最小约为0℃;当容积为0. 1 m^3的储藏箱面向冷冻需求时,可应用两片TEC1-12712型半导体制冷片结合水冷式热端和风扇下吹式冷端,能维持3 h箱体内温度不高于0℃。 相似文献
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Two-step preparation of Ag/tetrapod-like ZnO with photocatalytic activity by thermal evaporation and sputtering 总被引:2,自引:0,他引:2
Tian Tan Ying Li Yi Liu Bo Wang Xuemei Song Er Li Hao Wang Hui Yan 《Materials Chemistry and Physics》2008,111(2-3):305-308
A two-step method to synthesize metal–semiconductor heterostructure photocatalyst is presented in this research. Based on the tetrapod-like zinc oxide (T-ZnO) deposited by thermal evaporation, Ag/T-ZnO heterostructure is synthesized by RF magnetron sputtering method in this two-step preparation technique. The structure and the photocatalytic properties of the Ag/T-ZnO were studied in detail. The Ag/T-ZnO heterostructure exhibits better photocatalytic activity than that of the pure T-ZnO and there is an optimum sputtering time and sputtering power for the heterostructure's photocatalytic activity. The essential photocatalytic mechanism of this heterostructure have been discussed and the enhanced photocatalytic activity indicates the feasibility of this novel two-step method which may be developed to a promising synthesis technique. 相似文献
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Emery C.D. Swartz J.C. Casey H.C. Jr. Smith S.W. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1995,42(2):188-199
Optoelectronics and fiber optics can be used to miniaturize and improve the flexibility of the transducer cable and transducer handle of medical diagnostic ultrasound scanners. The reduction in size has gained importance as 2-D array transducers with up to 1000 independent channels become accepted to improve diagnostic ultrasound images. The authors describe the analysis, design, fabrication and testing of a prototype silicon photoconductive semiconductor switch (PCSS). The monolithic silicon PCSS was used in combination with an infrared semiconductor diode laser with a fiber optic “pigtail” to shock excite and burst excite a 2-D array transducer element resonant at 2.5 MHz. Optically controlled voltage, current, and ultrasound pulses are compared to those from conventional electronic shock excitation and narrow band Doppler pulses. The optically triggered ultrasound pulse for single shock excitation produced 30 V spikes at the 2-D array element with a fall time of 200 nsec and a rise time of 2 μsec with a peak current through the transducer element of 34 mA. An optically produced burst of eight pulses at a frequency of 2.5 MHz produced 11 V spikes at the transducer with a fall time under 100 nsec and a rise time of approximately 300 nsec. The peak current per pulse was 25 mA through the transducer element. These results show the feasibility of applying optoelectronic technology to replace conventional electronic transmitter technology 相似文献