ZnS修饰对ZnO纳米棒：P3HT复合薄膜I-V性质的影响

本文通过化学浴沉积法获得了直径约为50 nm, 长度约为250 nm的ZnO纳米棒阵列, 引入纳米ZnS对ZnO纳米棒进行表面修饰, 分别制备得到了具有ITO (indium tin oxides)/ZnO/Poly-(3-hexylthiophene) (P3HT)/Au和ITO/ZnO@ZnS/P3HT/Au结构的多层器件. 通过I-V曲线对比讨论了两种结构器件的开启电压, 串联电阻, 反向漏电流及整流比等参数, 认为包含ZnS修饰层器件的开启电压、串联电阻、反向漏电流明显降低, 整流比显著增强, 展现出更优异的电子传输性能. 光致发光光谱分析结果证实由于ZnS使ZnO纳米 棒的表面缺陷产生的非辐射复合被明显抑制, 弱化了电场激发下的载流子陷获, 改善了器件的导电特性. 关键词： ZnO纳米棒阵列 表面修饰 电流-电压特性     

弯曲表面上ZnO 亚微米棒阵列的制备

以ZnS和金属Zn粉末混合物为蒸发源以及金属Zn片为衬底,利用热蒸发气相沉积方法,在弯曲的金属Zn微球表面上,成功地获得了ZnO亚微米棒阵列结构。场发射扫描电镜研究表明:在弯曲的Zn微球表面,能自组织地生长出大量的截面为六边形的ZnO亚微米棒,这些亚微米棒的平均直径为500nm,长约1μm。棒的顶部是平滑的。能量散射X射线谱结果表明:合成的产品只存在Zn和O两种元素,其成分比例接近1∶1。没有观察到S元素。光致发射(PL)光谱显示:在387nm紫外波长处,出现一个强的半峰全宽为16nm的窄发光峰,可归属于ZnO的近带边发光,而509nm左右较弱的宽峰则源于界面缺陷态发光。这些研究结果说明我们所合成的这种ZnO亚微米棒阵列材料在紫外受激发射器件方面有着潜在的应用价值。     

双管气相沉积制备ZnxCd1-xS纳米棒及其光谱表征

通过物理气相沉积方法在镀金的硅基片上制备了ZnxCd1-xS纳米棒,并用VLS机制对生长机理进行了讨论.XRD分析表明产物是六方相的结晶体;SEM观察到纳米棒的长度为3～4微米,直径约为40纳米.PL谱显示有明显的红移现象,分析认为是由于ZnS对CdS晶格的轻微不匹配造成的,同时PL谱的峰型显示产物为ZnxCd1-xS...     

温和的苯热溶剂条件下GaP纳米棒的形成机理研究

采用金属Na，白磷和GaCl₃为原料，在温和的苯热溶剂条件下制备了直径为20—40nm，长度为200—500nm的GaP纳米棒和直径为20—40nm的球形颗粒.利用X射线衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)研究了反应条件对产物结晶性和形貌的影响.实验结果表明，当反应温度低于250℃时，产物基本上为GaP纳米棒，并随着反应温度升高，产物逐渐转化为球形纳米颗粒；当反应温度超过280℃时，产物完全为规则的球形.同时，GaP纳米棒的生长遵循SLS生长机理. 关键词： 纳米GaP 苯热 SLS生长机理     

金纳米棒二聚体结构的Fano共振

等离激元金属纳米结构中的Fano共振，由于其在超灵敏传感、超材料、光开关和非线性光学器件等方面的潜在应用而引起了广泛的关注。但在单颗粒尺度下单个金属纳米二聚体结构的Fano共振的实验研究仍然很少。本研究基于单颗粒光谱技术从实验上探讨了二聚体结构产生的Fano共振现象。利用种子生长法制备了等离激元共振峰分别在1 060 nm和700 nm的一长一短金纳米棒，通过L-半胱氨酸分子的静电吸附自组装构建首尾相连的金纳米棒二聚体结构，在暗场显微系统中表征了金纳米棒二聚体耦合前后的散射光谱。结果表明，短金纳米棒的明偶极模式与长金纳米棒的暗四极模式间的相消干涉在660 nm处产生了明显的Fano共振谷，同时基于有限差分时域（FDTD）方法的理论模拟散射光谱与实验结果能够较好地符合。这种自组装金纳米棒二聚体在等离激元传感和探测等方面具有广阔的应用前景。     

核-壳结构ZnS:Tb/CdS纳米晶的电致发光

利用微乳液方法合成出粒径为4nm的核．壳结构ZnS：Tb／CdS纳米晶。用XRD、TEM及荧光光谱等手段对合成的纳米晶的结构、形态和光学特性分别进行了表征。将ZnS：Tb／CdS纳米晶制作成有机-无机杂化结构电致发光器件,其结构为ITO／poly（3,4-ethylene dioxythiophene）：poly（styrene sulfonate）（PEDOT-PSS）（70nm）／poly（vinyleobarzale）（PVK）（100nm）／ZnS：Tb／CdS纳米晶（120nm）／2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline（BCP）（30nm）／LiF（1．0nm）／Al（100nm）。当驱动电压为13V时,可以测到Tb^3＋离子的两个特征峰。在电致发光光谱中未测到聚合物PVK的发光,说明电子和空穴是在纳米晶层上复合的。当驱动电压为25V时,得到器件的最大亮度为19cd／m^2。     

InSb纳米晶体的生长和吸收光谱的研究

采用在惰性气体中蒸发的方法获得了沉积在ZnS基片上的InSb纳米晶体,其平均尺寸随惰性气体的压强增加而增大.从实验测量的室温吸收谱上看到,当纳米晶体的平均直径从27.9 nm减小到24.2nm再到21.4 nm时,其吸收边分别向高能方向移动了0.0151 eV和0.0145 eV.用有效质量近似模型计算了半导体纳米晶体的吸收边相对其体材料的移动,将理论计算与实验结果进行了比较.     

电化学在ICF靶制备中的新应用

报道了近年来在电解加工技术制备理论密度金属薄膜和电沉积技术制备金属纳米丝阵列材料等领域取得的进展。采用硫酸+甲醇电解液体系获得了表面粗糙度小于30nm的钛膜。采用阳极氧化铝模板电沉积技术制备出长度约10μm、直径约300nm的金纳米丝阵列。主要讨论了电解液配方及电解加工参数的选择,金属纳米丝直径与长度的控制等问题。     

与掺杂浓度相关的ZnS∶Mn纳米粒子的发光性质

采用溶胶法制备了Mn掺杂的ZnS纳米粒子,探讨了掺杂离子浓度对ZnS∶Mn纳米粒子的晶体结构和发光性质的影响。通过X射线衍射（XRD）对样品的结构进行了表征,结果表明：所制备的ZnS∶Mn纳米粒子为立方闪锌矿结构,其在Mn离子的掺杂浓度达到6%时不发生分相,但随着掺杂浓度的增加,纳米粒子的平均粒径会减小。光致发光光谱和荧光光谱的结果表明：通过改变掺杂离子的浓度可实现对ZnS∶Mn纳米粒子590 nm附近荧光发射波长的调节。此外,研究了温度对纳米粒子形貌和发光性质的影响。高分辨透射电子显微镜（HRTEM）观察发现,经过50℃陈化1 h后的ZnS∶Mn样品的平均粒径增大约为20 nm,且加热陈化有利于ZnS∶Mn纳米粒子中Mn2＋在590 nm处产生荧光。     

室温氧化还原反应制备AgCuSe三元纳米棒

在室温下通过氧化还原反应制备了AgCuSe三元纳米棒.用X射线粉末衍射、透射电镜和X射线光电子能谱对产物进行了表征.X射线粉末衍射结果表明,产物是四方相AgCuSe;透射电镜结果表明,产物是纳米棒,其直径为5～20nm,长度为200～600nm;X射线光电子能谱结果表明,产物的纯度是很高的,没有单质Ag、Cu等杂质.应用化学热力学原理讨论了产物AgCuSe的生成机理.热力学计算表明,在这个反应体系中最终产物是纯AgCuSe.溶剂乙二胺不仅作为双齿配体与Ag+和Cu+形成稳定的配合物,而且还能溶解金属硒、增强硒的反应性,乙二胺在控制AgCuSe的成核和纳米棒的生长过程中起着重要的作用.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.