三维纳米线SAW气体传感器及报警器设计

该文提出了一种全新的三维纳米线结构的声表面波(SAW)气体传感器,详细阐述了谐振型SAW器件上纳米线制备与修饰改性设计,传感器信号提取电路设计及报警器设计等过程,最后研制出气体报警器样品。并利用沙林（GB）模拟剂对传感器性能指标进行了测试,该传感器的响应阈值低达2 mg/m3,响应时间仅约为20 s。结果表明,与传统二维结构的SAW气体传感器相比,三维纳米线结构的SAW气体传感器在响应阈值和响应时间上均有很大的提高。     

声表面波化学战剂气体传感器的研究

介绍了声表面波气体传感器的基本工作原理和设计方法,通过SAW芯片拓扑结构、敏感膜、覆膜工艺和信号处理电路等方面的优化,研制出两种SAW化学战剂气体传感器,具有灵敏度高、响应和解吸附快,抗干扰能力强的特点。     

声表面波气体传感器研究进展

从机理模型构建、物理功能结构优化两方面出发对覆盖聚合物敏感膜的高性能声表面波(SAW)气体传感器技术进行了研究和探讨.实验研制了一种以具有高频率稳定性的声表面波延迟线型振荡器为传感元,结合六氟异丙醇基聚硅氧烷敏感膜的SAW传感器,开展了针对DMMP的检测实验,检测下限与检测灵敏度分别达到了0.04 mg/m3和485 Hz/mg/m3.     

433.92 MHz声表面波水果气体传感器研究

为监测水果在仓储及运输等过程中的新鲜程度,研制了一种以声表面波(SAW)单端谐振器为载体的SAW水果释放气体传感器。运用原位一步聚合法制备了聚苯胺气敏材料,在器件的敏感区域上用滴涂法涂覆敏感膜。实验结果表明,该传感器在室温条件下,对水果气体具有灵敏度高,响应恢复快等特性。对敏感机理进行了理论分析。     

基于延迟线理论的无源声表面波气体传感器

针对单输入、单输出及双输入、双输出换能器构成的声表面波(SAW)气体传感器存在的缺陷,研究一种无线无源、温度可测的气体传感器。基于声表面波的延迟线理论,利用叉指换能器的转换能量原理,对叉指换能器及反射器进行合理布局,并使3个反射器之间互为参考反射器,获得一种新型的声表面波气体传感器。该设计减少了传感器中信号间及环境温度等因素对测量的干扰,提高了传感器的灵敏度和测量准确度。该传感器具有结构简单、无线无源等特点,适合在不宜接触的复杂工程环境下工作。     

气体声表面波传感器的研究进展

主要从声表面波(SAW)结构和敏感膜的角度综述了SAW气体传感器的研究现状。重点分析了国外出现的换能器新型结构,对其优点进行了初步分析,并和传统的SAW气体传感器结构做了比较,指出这些新结构尽管存在一些缺点,目前还不能取代传统的通用式结构,但是在某些特殊场合具有传统结构所不具备的优点。在敏感膜方面,主要从新材料方面入手,分析了目前主要使用的敏感膜材料,并结合SAW气体传感器的发展趋势,总结出敏感膜的发展方向。同时,对SAW气体传感器的其他组成部分如衬底材料和信号处理电路也作了简单的回顾,最后结合国内外研究成果对SAW气体传感器的发展做了展望。     

一种新型高频率稳定度的SAW振荡器

作为声表面波(SAW)气体传感器的关键元件,SAW振荡器的频率稳定度直接影响到传感器的灵敏度和检测下限。因此,提高SAW振荡器的频率稳定度是传感器研究的关键。该文在ST石英基片上研制了一种具有低插入损耗(10 dB内)、单一模式控制的SAW双延迟线及振荡器,其频率稳定度达0.1×10-6量级,同时还分析了作为频控元件的延迟线品质因数及振荡电路温度对振荡器频率稳定度的影响。     

碳纳米管聚苯胺薄膜SAWSO2传感器的实验研究

以128°Y-LiNbO3晶体上实现的双声路声表面波(SAW)器件为载体,在器件的测量声路上制作了对SO2气体具有敏感作用的碳纳米管聚苯胺薄膜,提出了一种基于碳纳米管聚苯胺薄膜的SAW SO2气体传感器.该传感器中的双声路结构消除了因外界测量条件改变引起的测量误差,提高了传感器的可靠性和准确性.利用原位法制备的碳纳米管聚苯胺增加了SO2气体的吸附面积,提高了传感器的灵敏度.实验结果表明,基于碳纳米管聚苯胺薄膜的SAW SO2气体传感器在测量范围内对各种浓度的SO2气体具有好的响应特性;当输入体积分数为1×10-6时,传感器的响应灵敏度约为8.3 kHz,比单一聚苯胺薄膜高1.8 kHz.此外,该传感器也具有更好的线性特性.     

声表面波延迟线振荡器为核心的气体传感器

声表面波(SAW)器件的工作频率随基片表面上的负载质量变化而发生漂移,通常利用这一性质作气相分析与检测,已经有了若干用SAW延迟线器件制成的化学传感器。传感器表面涂着一层有化学选择性的薄膜,这一涂层则在化学分析时有选择地吸收待测气体分子,涂层在吸收了气体后发生一些物理变化,因而这种传感器的灵敏度与SAW延迟线表面上的涂层对气体的吸收量有关。许多实际使用的传感器是用双SAW延迟线组成的,它们集成在一片基体上,并在一个延迟线表面上涂上气体吸附薄膜,而另一个则不涂任何物质。 本文讨论了这种传感器的若干问题,如温度影响、响应时间以及频率变化与气体浓度间关系的非线性。最后提出了在传感器应用时的改进方法与措施。     

一种新型的角速率传感器--声表面波陀螺

声表面波(SAW)器件具有无源、无线、微型、抗冲击力强，灵敏度高等优点。用它制作角速率传感器——SAW陀螺已成为研究热点。概述了SAW陀螺的应用及发展；着重分析了SAW陀螺两种结构模式的工作原理；指出SAW陀螺设计的关键是如何得到合适的参考振动速度，而使其省掉悬浮振动机构成为简单的单平面结构；提出了亟待研究解决的几个问题。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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