多层透射式光纤氢气传感器的氢敏光谱特性

针对多层透射式光纤氢气(H₂)传感器其特殊的多层结构造成了类似于F-P 腔 效应的周期性光谱特性变化尚未可知问题,构建了一种适用于多层 透射式探头的原位H₂敏光谱观测系统,通过实验研究了在不同H₂浓度下这种多层膜 结构的光谱特性, 讨论了光源波长变化对传感器测量稳定性的影响规律,为进一步提高传感器性能奠定了实 验基础。实验 结果表明,光源波长变化对传感器测量的可靠性有显著影响,但是通过扫描波长的方式测 量可以有效避免这类H₂传感器的波长漂移问题,达到较高的测量可靠性。     

TDI CCD宽波段光谱响应度的高精度检测

为了解决TDI CCD光谱响应度检测精度较低、检测方法不够准确等问题,提出了一套更为科学而准确的高精度TDI CCD光谱响应度检测方法。首先,改进了TDI CCD视频信号处理方法;其次,选用不同窄带波长的LED阵列作为光源,建立一种方便而准确的宽波段光谱响应度检测系统;然后,改变TDI CCD接收的辐射照度并检测TDI CCD输出信号,提出一种高精度TDI CCD光谱响应度检测方法;最后,计算所有窄带波长的LED对应的TDI CCD光谱响应度,绘制TDI CCD在400～900nm波长范围内的光谱响应度曲线。实验结果表明:此方法覆盖了400～900nm的宽波长范围,检测方便准确,同时,光谱响应度检测误差达0.025。     

LED照明的视觉与非视觉随色温变化研究

为了响应CIE最近提出的“照明应该综合考虑光的 视觉和非视觉效果”号召,寻找视觉与非视觉参数之间的关系。选择8种大色温范围(2678 K－7258 K)的LED照明光源,特别是超低色温LED,采集380 nm可见光波段光谱分布数据。利用OSRAM COLOR CALCULATOR色度分析软 件及MATLAB,计算分析了6个视觉参数(显色指数、色容差、色品质度、色纯度、主波长、 暗明比S/P)及4个非视觉参数(节律因子KC、蓝光危害因子KB、400nm蓝光占比P、1931 CIE-XYZ标准色度系统Z值)随色温变化。结果表明:8种不同色温LED照明6个视觉参数随色 温变化均较为复杂,不便直接找到6个视觉参数随色温变化关系;4个非视觉参数均随色温的 增加呈线性递增关系,表达式分别为:KC=0.118+6.069×10－4×T_c、KB=1.625×10－4+1.682×10－7×T_c、Z=0.014+5.240×10－5×Tc、P=－0.065 37+0.005×T_c。另外,LED照明蓝光危害因子KB与400nm蓝光占比P表达式为:KB=－1.575×10－4+3.326×10－5×P,相关系数平方R²=0.979。以上结论可为LED照明光品质及光生物安全随色温变化 分析,特别是LED照明视觉与非视觉的协调发展提供参考。     

基于自适应噪声抵消的光电二极管阵列检测器

由于普通光电二极管阵列检测器(PDAD)无法克服光源波动造成的影响,设计开发了一种采用自适应噪声抵消技术的PDAD。该检测器采用分光镜实现光的分束和合束,采用凹面光栅实现分光系统,PDA作为光电接收元件。在斩光器和后续电路的配合下,实现了在同一PDA上信号光光谱、参考光光谱和暗电流的分时测量。由于采用参考光的吸光度信号对样品光的吸光度信号进行自适应噪声抵消,可以有效降低光源光强波动的影响,使基线短期噪声降低1×10-5AU,漂移降低为1×10-4AU/h。     

基于多模激光关联光谱的甲烷气体检测技术

为提高多模激光吸收光谱的灵敏度,将多模二极 管激光关联光谱、长程吸收技术和波长调制光谱结合,建立了一 套具有高检测灵敏度和高稳定性的气体检测系统。采用1675nm多模激光器作为光源,以光程为100 m的离散镜片型 多通 池作为气体吸收池,利用甲烷的2ν₃泛频带吸收谱线,通过计 算待测气体和参考气体的二次谐波信号峰值之间的关系,实 现了对CH₄气体的测量。实验在室温和20.265 kPa(即0.2个标准大气压)条件下进行 ,CH₄浓度范围为1.00×10－5－1.10×10－2。实验结果表明,CH₄浓度测量值与真实值之间具有良好的线性关系, 其线性度为0.997,系统的测量准确度为 3.50%,对浓度为2.60×10－6的气体样 品在30 min内的连续测 量表明系统稳定度优于2.53%。本方法具有操作简单、稳定性 好、灵敏度高和环境适应性强等优点,在工业过程控制和环境监测中具有广阔的应用前景。     

差分吸收光谱测量中LED光源恒温控制的实现

提出了一种差分光学吸收光谱（DOAS）测量中LED光源的恒温控制方法。采用半导体制冷片作为控温元件来控制LED温度,应用PID算法动态调节半导体制冷片的工作电流,实现了DOAS测量过程中LED光源的温度恒定。介绍了恒温控制系统的硬件设计和软件流程,并对控温效果和LED谱的稳定性进行了测试。测试结果表明,提出的恒温控制方法能有效克服环境温度变化对LED光源温度的影响,温度控制精度达到了±0.1℃。在相同的测试条件下与无恒温相比,具有恒温功能的LED光源剩余噪声明显偏低,进一步验证了设计方案的可行性。     

一种中红外差分甲烷检测仪的研制

根据甲烷(CH₄)分子在中红外波段的吸收特 性并利用宽光谱红外热辐射光源(IR55), 研制了一种基于中红外吸收光谱技术的双通道差分CH₄检测仪。通 过对双通道探测器(3.31 μm和3.90μm)输 出的两路信号进行差分处理,有效抑制了系 统噪声。给出了系统的检测原理和结构,表征了光源和探测器的光学特性。为了提高聚光效 率并增大光程,设计制作了球面反射镜开放气室,其半径约20cm。 配备了16种不同浓 度的CH₄气体样品,开展了气体标定实验,得到了气体浓度 与双通道信号幅值电压的关 系表 达式。 误差实验结果显示, 对16种气体样品的检测误差小于12.4%。 对体积分数为 5×10－4的CH₄气体样品开展的长达10h的浓度测量实验 表明,检测结果的相对波动范围 为±10%。对测得的实验结果进行数理统计,其标准差为2.06×10－5,进而得到该检测仪的检测下限约为6.18×10－5。     

COB封装全光谱LED光源及其光电特性

为了提高光源的显色指数,设计、制作一种COB封装的全光谱LED光源,通过在设计中增加峰值波长415nm的紫光LED芯片和发光峰值波长497nm、655nm的荧光粉,弥补了普通LED光源在紫光、蓝绿光和红光等光谱区间的能量分布不足。实验结果表明,发光效率达到103.34lm/W,全光谱LED光源显色指数高达99.38,接近日光100的显色指数,能够满足高质量照明领域对光源显色性的要求。     

检测天然气中H2S气体浓度的光子带隙光纤传感器

为消除光源不稳定、光电器件的热零点漂移以及零 点漂移对测量准确度的影响,基于差分吸收检测法,设计一种检测天然气中H₂S气体浓度 的高稳定性、高灵敏度的光子带隙传感器。为提高系统响应,采 用4段串联的空芯光子晶体光纤(HC-PBF)作为气体传感探头。对不同组分浓度 的H₂S和CO₂气体进行了检测,结果表明,系统响应时间为53s, 测量灵敏度可达2×10－6 mol/L。     

非稀土红色荧光粉Mn4+:Li2TiO3发光特性研究

利用高温固相法成功合成了非稀土类红色荧光粉 Mn⁴⁺:Li₂TiO₃,并对所制得的样品进行X射线衍射(XRD)、吸收谱和荧光发射谱等 表征。在波长为475nm的LED蓝光照射时,获得了最大强度位于〖J P 〗682nm波长处的红色荧光,量 子效率约为10%,其对应Mn⁴⁺自旋²Eg→⁴A 2g。计 算了晶体场强度因子Dq和Racah参数B、C,并据此分析了Mn⁴⁺在Li₂TiO₃中的电 子云重排效应。通 过改变掺杂浓度,分析了Mn⁴⁺掺杂在Li₂TiO₃中的浓度淬灭效 应。最后进行了LED白光性能 测试。     

VOLTE容灾机制研究及优化方案

_{本文首先对VOLTE现网网络结构及容灾机制进行研究分析,发现现存容灾机制中存在的缺点和不确定性,针对其中的问题,针对性地进行了深入研究和分析,创新的提出了1种快速容灾抢通方案,以达到提升VOLTE业务运维能力和用户业务感知的目的。}     

Calculation of energy band gaps in quaternary iii/v alloys

The dielectric theory of electronegativity is applied to the calculation of the compositional dependence of the energy band gap for quaternary III/V alloys of type A_l-xB_xC_1-yD_y and A_1-x-yB_xC_yD. The departure from linearity of E_G versus x and y is taken to be the sum of two terms, the intrinsic or virtual crystal term and the extrinsic term due to effects of aperiodicity which for one type of alloy may occur on both sublattices. Rather than simply treating the quaternary as an average of the bounding ternary systems, as has been common in the past, the intrinsic departure from linearity is calculated by assuming E_h,i,C, and D_av to vary linearly with x and y. The result is a smaller intrinsic deviation from linearity and a much better fit to existing data in the system Ga_1-xIn_xAs_1-y P_y. The calculation is also applied to three systems where no data exist but which are of great interest because of their potential application for the fabrication of lattice matched tandem solar cells: Ga_l-xA1_xAs_l-ySb_y. Ga_1-x-yA1_xIn_yAs, and GaAs_1-x-yP_xSb_y.     

新形势下河北移动全业务支撑策略研究

随着铁塔公司的成立及国家在“宽带中国”“提速降费”等一系列通信领域的重大战略实施,全业务运营越来越成为河北移动保持领先,实现卓越的重要支点。基于此河北移动启动大规模综合业务区建设,由传统传输网围绕基站建设转向全业务支撑。河北移动将综合业务区建设与全业务机房的选取统筹安排,建设综合业务区与全业务机房的联络光缆,将综合业务区光缆网成为承载重要集客数据专线和4G拉远站的载体,合理、有序、迅速实现“一张光缆网”的建设,鼎力支撑全业务及4G的发展。     

Nickel silicidation techniques for strained Si1?xGex, Si1?x?yGexCy, and Si1?yCy alloys material-device applications

A nickel silicide process for Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy materials compatible with Si technology has been developed. Low-resistivity-phase (12–20 μΘ cm) nickel silicides have been obtained for these alloys with different low sheet-resistance temperature windows. The study shows that thin (15–18 nm) silicide layers with high crystalline quality, smooth silicide surface, and smooth interface between silicide and the underlying material are achievable. The technique could be used to combine the benefits of Ni silicide and Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloys. The technique is promising for Si or Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy-based metal-oxide semiconductor, field-effect transistors (MOSFETs) or other device applications.     

Characterization of a rapid thermal anneal TiNxOy/TiSi2 contact barrier

In this paper, the physical and electrical properties of a TiN_xO_y/TiSi₂ dual layer contact barrier are reported. The TiN_xO_y/TiSi₂ barrier was formed by rapidly annealing a Ti thin film on Si in an N₂ ambient. During this process, the Ti film surface reacts with N₂ to form a TiN_xO_y skin layer and the bulk of the Ti film reacts with Si to form an underlying TiSi₂ layer. The influences of rapid thermal anneal (RTA) conditions on the TiN_xO_y layer were investigated by varying the RTA temperature from 600 to 1100° C and cycle duration from 30 to 100 s. It is found that the resulting TiN_xO_y and TiSi₂ layer thicknesses are dependent on RTA temperature and the starting Ti thickness. For a starting Ti thickness of 500Å, 150Å thick TiN_xO_y and 800Å thick TiSi₂ are obtained after an RTA at 900° C for 30 s. The TiN_xO_y thickness is limited by a fast diffusion of Si into Ti to form TiSi₂. When a Ti film is deposited on SiO₂, Ti starts to react with SiO₂ from 600° C and a significant reduction of the SiO₂ thickness is observed after an RTA at 900° C. The resulting layer is composed of a surface TiN_xO_y layer followed by a complex layer of titanium oxide and titanium suicide. In addition, when Ti is depos-ited on TiSi₂, thicker TiN_xO_y and TiSi₂ layers are obtained after RTA. This is because the TiSi₂ layer retards the diffusion of Si from the underlying substrate into the Ti layer. NMOSFETs were fabricated using the TiN_xO_y/TiSi₂ as a contact barrier formed by RTA at 900° C for 30 s and a significant reduction of contact resistance was obtained. In addition, electromigration test at a high current density indicated that a significant improvement in mean time to failure (MTF) has been obtained with the barrier.     

Low pressure metalorganic chemical vapor deposition of InP and related compounds

The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga_0.47In_0.53 As and Ga_xIn_1-xAs_yP_1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm² V⁻¹S⁻¹ at 300 K and 58 900 cm² V⁻¹ S⁻¹ at 77₂K, and for GaInAs was 11900 cm² V⁻¹ S⁻¹ at 300 K, 54 600 cm² V⁻¹ S⁻¹ at 77 K and 90 000 cm V⁻¹S⁻¹ at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current.     

Transport properties of thermoelectric materials for coolers

The Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of cooler grade, p-and n-type ternary alloys of Bi₂Te₃-Sb₂Te₃-Sb₂Se₃ were measured between 10 and 300 K. Between 300 K and about 150 K the temperature dependence of the transport properties can be explained by assuming nondegeneracy and a lattice scattering mechanism. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p-type alloys.     

Processing of large YBa2 Cu3Ox domains for levitation applications by a Nd1+x Ba2−x Cu3 Oy-Seeded melt-growth technique

YBa₂Cu₃O_x domains for levitation applications have been produced by a seeding technology that includes Nd_1+x Ba_2−x Cu₃O_y seeds and melt-processing technologies such as conventional melt-textured growth, melt-texturing with PtO₂ and Y₂BaCuO₅ additions, and the new solid-liquid-melt-growth technology. Large domains (∼20 mm) with high levitation forces (F₁ up to 8.2 N) have been produced. The reproducibility of the results is good, and the capability of producing a large number of pellets in a single batch indicates good potential for the production of large amounts of this material.     

基于InP衬底的晶格失配In0.68Ga0.32As的MOCVD生长及其特性研究

采用MOCVD生长技术在InP衬底上成功实现了晶格失配的3μm In0.68 Ga0.32As薄膜生长.通过As组分的改变,利用张应变和压应变交替补偿的InAsxP1-x应变缓冲层结构来释放由于晶格失配所产生的应力,在InP衬底上得到了与In0.68Ga0.32 As晶格匹配的InAsxP1-x“虚拟”衬底,通过对缓冲层厚度的优化,使应力能够在“虚拟”衬底上完全豫弛.通过原子力显微镜(AFM)、高分辨XRD、透射电镜(TEM)和光致发光(PL)等测试分析表明,这种释放应力的方法能够有效提高In0.68 Ga0.32 As外延层的晶体质量.     

The effect of Tl2Te3 on the properties of the solid solution (Sb2Te3)0.75.(Bi2Te3)0.25

The effect on transport properties of the addition of 0.5-5% Tl₂Te₃ to p-type solid solutions of antimony and bismuth tellurides was studied. It was found that the addition of Tl₂Te₃ caused a lessening of the increase of hole concentration as low temperatures were approached, resulting in a slower decrease of the Seebeck coefficient with a decrease in temperature. In partial fulfillment of M.Sc. degree, Hebrew University, Jerusalem. Permanent address, Dept. of Inorganic and Analytical Chemistry, Hebrew University, Jerusalem.