An AES study of surface segregation of AgAu alloys with ion bombardment and annealing

Equilibrium segregation and selective sputtering in the surface of AgAu alloys have been investigated systematically with argon ion bombardment and with annealing by means of AES measurements. Slight enrichment of Ag was observed on the alloy surfaces after the annealing of the alloys at 550°C, while relatively large enrichment of Au was observed on the ion-bombarded surfaces with the use of Au (240 eV) and Ag (300 eV) Auger electrons. With the aid of other Auger electrons with different escape lengths, it was found that the concentration varies with distance from the surface within the sampling depth of the Auger electrons. On the basis of the above facts, the depth profiles were proposed for the annealed and the ion-bombarded surfaces. The uppermost surface layer is enriched more with Ag than the apparent AES observations on both the ion-bombarded and the annealed surfaces. The proposed depth profiles on both the surface layers were compared with previous results by different authors.     

激光辐照对热退火金属/掺氟二氧化锡透明导电薄膜光电性能的影响

采用532 nm纳秒脉冲激光对热退火的铝(Al)/掺氟二氧化锡(FTO)、铜(Cu)/FTO和银(Ag)/FTO三种双层复合薄膜表面分别进行处理, 结果显示薄膜样品的光电性能都得到提高.其中, 热退火Ag/FTO薄膜的平均透光率(400–800 nm)增幅最大, 从72.6%提高到80.5%, 主要是由于其表面产生了具有减反增透作用的光栅结构.激光辐照后热退火Ag/FTO薄膜的导电性也略有提高, 其方块电阻从5.6 Ω/sq下降到5.3 Ω/sq, 原因主要是激光辐照的热效应造成的退火作用使薄膜的晶粒尺寸增大, 减少了晶界散射而使载流子迁移率提高.计算结果显示, 激光辐照后热退火Ag/FTO薄膜的品质因子从0.73×10^-2Ω^-1增大为2.16×10^-2Ω^-1, 表明其综合光电性能得到显著提高.激光辐照可同步实现薄膜表面光栅结构的制备和附加退火作用, 这为金属层复合透明导电薄膜光电性能的综合优化提供了新的思路.     

Synthesis and structural investigation of Pd/Ag bimetallic nanoparticles prepared by the solvothermal method

Pd/Ag bimetallic nanoparticles have been synthesized successfully by reducing PdCl₂ and AgNO₃ mixture in ethylene glycol solution using the solvothermal method. The prepared samples have been characterized by UV–vis, XRD, TEM, HRTEM, EDS, and XPS, respectively. Moreover, the bimetallic particles possess alloy and core-shell structure from the HRTEM images. Here, the lattice fringe spacing of Pd/Ag bimetallic nanoparticles corresponds to its (111) plane, which is between that of the Pd and Ag nanoparticles prepared under the same conditions. Furthermore, the possible formation mechanism and factors influencing the formation of Pd/Ag bimetallic nanoparticles, such as reaction temperature and time, have also been investigated.     

Substance identification by depth resolved spectroscopic pattern reconstruction in frequency domain optical coherence tomography

We analyze a method to extract additional depth resolved spectroscopic information from frequency domain optical coherence tomography (FDOCT) data. The reconstruction of depth resolved spectra is obtained by a Fourier transform of the individual peaks in the complex FDOCT depth profiles. We demonstrate a validation of this concept with theoretical simulations and with accurate experimental studies on a multilayer sample with four different characteristic absorbers. The spatially resolved spectroscopic patterns of all individual sample layers are calculated from the depth resolved reconstructed spectra. With an additional pattern recognition algorithm, these reconstructed patterns are compared automatically to the spectral characteristics of the expected substances. This provides an allocation of the reconstructed spectra to the substances with high reliability. Thus, we present an automated substance identification directly from conventional FDOCT data, which increases significantly the information content of the image.     

Fabrication and characterization of Pd/Ag alloy hollow spheres by the solvothermal method

Pd/Ag alloy hollow spheres have been synthesized in ethylene glycol solution by the solvothermal method and have been characterized extensively. TEM results have revealed the formation of Pd/Ag hollow spheres. Moreover, HRTEM results confirmed the formation of Pd/Ag alloy spheres, where the lattice fringe spacing is 0.229 nm corresponding to the (111) plane of Pd/Ag alloy. SEM, XRD and UV–vis results have further suggested the formation of alloy hollow spheres. The preliminary results showed the reaction time may be an importance factor influencing the formation of Pd/Ag alloy hollow spheres.     

ZnO/Zn界面对纳米ZnO薄膜光学性质的影响

采用氧等离子体辅助电子束蒸发金属Zn后低温退火的方法制备纳米ZnO薄膜。利用X射线衍射(XRD)谱、拉曼(Raman)谱、X射线光电子能谱(XPS)以及光致发光(PL)谱等手段,分析了退火温度及ZnO/Zn界面对样品的结构和发光性质的影响。Raman结果表明随着退火温度的升高,界面模式(Es)振动减弱并向低波数方向移动。当退火温度为400℃时,界面振动消失,Zn全部转化成具有六方纤锌矿结构的ZnO,得到化学配比的纳米ZnO薄膜。PL谱表明,经400℃退火处理的样品紫外发射最强,发光性质最好。     

Selective metal pattern formation and its EMI shielding efficiency

A novel method for selective metal pattern formation by using an enhanced life-time of photoexcited electron-hole pairs in bilayer thin film of amorphous titanium dioxide and hole-scavenger-containing poly(vinyl alcohol) was proposed. By UV-irradiation through photomask on the bilayer film, the photodefined image of photoelectrons could be easily and simply produced, consequently resulting in selective palladium (Pd) catalyst deposition by reduction. The successive electrolessplating on Pd catalysts and electroplating on electrolessplated pattern were possible. Furthermore, the electromagnetic interference shielding efficiencies of the metal mesh patterns with various characteristic length scales of line width and thickness were investigated.     

Effect of annealing temperature on determining trap depths of quartz by various heating rates method

The aim of this study is to determine the trap parameters (trap depth E, frequency factor s) of quartz using various heating rates method and also to investigate the effect of annealing temperature on determining trap depths. The method is based on the positions of the thermoluminescence peaks, obtained from the change in temperature of the peak at maximum caused by changing the heating rate at which the sample is measured. In the present work, powder quartz samples were annealed first at different temperatures before irradiation. Then samples irradiated to different doses were measured with a TL reader at different heating rates and the glow curves were recorded. In order to calculate the trap depth E and the frequency factor s, the glow parameter T_m was determined experimentally from the glow curve by measuring the shift of the maximum peak temperature depending on heating rate β. The calculation of trap parameters was repeated for each annealing temperature. Then the effect of annealing temperature on trap depths calculated by the various heating rates method was evaluated.     

微腔器件中金属镜反射相移与穿透深度研究

针对金属反射相移计算时电磁波相位符号表述混乱导致错误的穿透深度计算结果现象,通过理论推导得出电磁波两种相位表述符号下对应的金属复折射率有两种不同形式,从而导致金属反射相移位于不同的象限,穿透深度和反射相移之间的关系式也相应的有两种结论.并通过调节Ag膜的厚度制作了一系列对称全金属λ/2腔器件,器件结构为Glass/Ag/LiF/Ag.通过比较Ag膜穿透深度的实验结果和计算值,验证了其中一种金属穿透深度公式的正确性.     

The reflectivity of Mo/Ag/Au ohmic contacts on p-type GaN for flip-chip light-emitting diode (FCLED) applications

The Mo/Ag/Au contact for flip-chip light-emitting diode (FCLED) applications is examined on its contact resistance and light reflectance. A high reflectance of 90% is achieved in un-annealed contact, but a strong inter-diffusion of ohmic metals and GaN during the annealing process is found to result in poor reflectance (55% at the wavelength of 465 nm). The secondary ion mass spectrometry (SIMS) depth profiles indicate that a wide inter-diffusion region existed in the annealed contacts; thus the low reflectivity of the Mo/Ag/Au-annealed contacts can be attributed to the strong inter-diffusion of Au and Ag.     

The anomalous RHEED patterns observed from (111)Ag-(111)Cu bilayers

RHEED patterns obtained from thin expitaxial bilayers consisting of Ag grown on smooth (111)Cu surfaces have been shown by Gradmann and Krause to contain anomalous reflections. Previously, these reflections were interpreted as due to a regular arrangement of interfacial dislocations or to multiple diffraction effects. In the present work a thin film technique was used to form smooth, easily detachable (111)Ag/Cu bilayers from which RHEED patterns containing these extra reflections were obtained. These films were grown, annealed, and examined in situ by UHV-RHEED techniques. They were then removed from the vacuum system, detached from their substrates and examined by TEM and TED. Thus, contrary to previous work, the present observations consisted of a series of experiments using RHEED, TED, and TEM carried out on the same specimen. No evidence was obtained to indicate that the anomalous reflections were due to interfacial dislocations. Rather, all the observed phenomena could be explained entirely by multiple diffraction effects.     

Depth profiles of Ag nanoparticles in silicate glass

Silver nanoparticle composite glass has been synthesized by ion exchange and a subsequent thermal treatment method. Transmission electron microscopy (TEM) and ultraviolet-visible spectrometry were used to study the depth profiles of Ag nanoparticles in silicate glass. Results indicate that Ag nanoparticles are nearly spherical in shape with a single-crystalline structure. Also, the volume fraction of Ag nanoparticles is very high in the surface layer of 5 μm, and then decreases slowly across the depth of 30 μm, thereafter the volume fraction reduces quickly to zero at the depth of 100 μm. The plasmon resonance bi-absorptions in the surface layer of the annealed specimen at 600 °C can be attributed to bi-modal distributions of Ag nanoparticles in the layer. The bi-modal distributions can be explained by the Ostwald ripening theory. PACS 81.05.Pj; 81.07.-b; 68.37.Lp     

X射线衍射多晶谱计算机深度层析技术探索

提出了一种可用于将来自不同真实深度处的X射线衍射谱信息各自分离出来的技术方案,可以得出不同深度处的衍射强度、峰位和线形.该方法是定量和无损的,并且其深度尺度是真实尺度.此外并提出了吸收深度的概念.这一技术可称为直接法X射线衍射计算机深度层析技术,其可行性用Ni/Mo.双层膜样品进行了初步验证.该方法可应用于定量无损地测量峰形、峰位和峰强的深度剖面,并有可能用于界面层分析. 关键词：     

Application of mechanical scanning to ion implantation

Abstract

Atomic depth profiles from Be-implanted Si have been examined as a function of implant fluence and annealing, and the results have been correlated with theoretically calculated implantation induced damage profiles. The Be atomic depth profiles were obtained by secondary ion mass spectrometry (SIMS) techniques from samples implanted at 300 keV to fluences ranging from 2 × 10¹² to 10¹⁵ cm^?2. Subsequent to annealing at 600°C for 30 min, the Be SIMS profiles exhibited anomalous redistribution effects. The Be profiles obtained from the annealed samples had the same general features as the depth distribution of implant energy deposited into damage, based on Brice's¹ calculations. The correlation of the SIMS atomic profiles and the theoretical damage profiles indicated that Be “decorates” the implantation induced damage regions while redistributing during the annealing process.     

Solvothermal synthesis of high hydrogen permeable Pd/Ag alloy particles and their hydrogen transport properties

Pd₇₆Ag₂₄ nanoparticles with high purity and a face-centered cubic structure were prepared using a solvothermal method. The lattice parameter of the Pd₇₇Ag₂₃ nanopowders (space group 225Fm3m) was calculated to be a?=?3.9382 Å. The primary particle size was calculated to be 7.7 nm from the X-ray line width using the Scherrer formula, and the interplanar distances was estimated to be 2.272 and 2.000 Å based on indexing on the (111) and (200) plane, respectively. These values are slightly larger than those of pure Pd and smaller than Ag in the (111) plane. The linear relationship of the hydrogen permeation flux with the square root of the hydrogen partial pressure gradient across a 0.26-mm-thick Pd/Ag-YSZ cermet membrane confirmed the major hydrogen transport through the Pd/Ag phase of cermet membranes. The Pd/Ag-YSZ cermet membranes showed significantly higher hydrogen permeation flux than the Pd-YSZ cermet membrane, even though the activation energy for the Pd/Ag alloy cermet membranes showed slightly higher values than that of the Pd cermet membranes. The hydrogen–oxygen dual flux through Pd/Ag-YSZ cermet membranes was confirmed by the maximum hydrogen production by combining the ability of hydrogen production from water with the function of hydrogen separation on composite membranes     

聚合物P3HT在不同退火温度下的空穴传输特性

运用交流阻抗方法系统研究了单空穴注入型器件ITO/PEDOT/P3HT/Ag（P3HT：poly（3-hexylthiophene））在多种退火温度下的电容-频率变化关系,推算出样品中相应条件下的空穴迁移率,发现退火温度对空穴迁移率有明显影响,未经过退火的样品空穴迁移率为10^-4cm²/Vs数量级,迁移率数值基本不随电场强度的改变而变化,退火后样品的空穴迁移率有明显提高,约为10^-3cm²/Vs数量级,此时,空穴迁移率 关键词： 空穴迁移率 聚合物 电容-频率特性     

Effects of annealing temperature on YAG:Ce synthesized by spray-drying method

In this report, YAG:Ce phosphors were synthesized by spray-drying method. The effects of annealing temperature on crystal structure, morphology and photoluminescence property (PL) of as-prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and spectrofluorometer, respectively. The XRD patterns showed all the samples are in consistence with a single garnet phase, and the location of strongest peak shifts to smaller angle with increasing the annealing temperature. The SEM micrographs revealed the sample annealed at 1200 °C appears to be a spherical polycrystalline aggregate; as the samples were annealed at 1300?1400 °C, spherical grains obviously grow up; but the sample annealed at over 1400 °C forms an irregular bulk. The emission spectra of samples indicated the PL of samples annealed at 1200?1400 °C improve with increasing the annealing temperature because of the diffusion of Si⁴⁺ ions; whereas the PL of sample annealed at the temperature over 1400 °C decreases likely resulting from inflection effects of multiangular shape of grains. Therefore, the samples annealed at 1400 °C are suitable for gaining phosphor with high brightness and good morphology.     

Ag+-Li+离子交换制作Er3+/Yb3+共掺磷酸盐玻璃平面光波导

制备了化学稳定的Er3+/Yb3+共掺的磷酸盐玻璃,并在其中制作了用于光放大器和激光器的平面光波导.这种磷酸盐玻璃的失重速率为4.7×10－5g·cm－2·hr－1,小于Kigre公司商业化的磷酸盐玻璃QX/Er的失重速率.采用Ag+-Li+交换技术制作了平面光波导并用m-线光谱在632.8 nm测量了平面光波导的有效折射率.根据反WKB法得到折射率形貌,计算了离子交换参数如:离子交换深度、表面折射率,折射率改变和扩散系数等.     

Ag-Cu离子注入玻璃后不同气氛退火的光吸收研究

采用MEVVA源（metal vapor vacuum arc ion source）引出的强束流脉冲Ag,Cu离子先后注入到SiO₂玻璃，x射线光电子能谱仪（XPS）分析显示Ag，Cu大多仍为金属态，有部分氧化态Cu存在.透射电镜观察分析和光学吸收谱都表明在衬底中形成了纳米合金颗粒.结合有效媒质理论，得到模拟的光学吸收谱，与实验结果基本符合，较好地验证了以上结论.样品退火后颗粒发生分解，分解的颗粒在氧化气氛下被氧化，且有部分向样品表面蒸发；在还原气氛下氧化态元素被还原并成核生长.故 关键词： 离子注入 纳米颗粒 退火 光学吸收率     

Thermally induced effects on structural and electrical properties of selenium-rich Cd-Se thin films

The effect of annealing in nitrogen atmosphere on structural and electrical properties of selenium rich CdSe (SR-CdSe) thin films deposited by thermal evaporation onto glass substrates were studied. X-ray diffraction (XRD) patterns showed that the as-prepared films were amorphous, whereas the annealed films were polycrystalline. Analyzing XRD patterns reveals the coexistence of both Se and CdSe crystalline phases which exhibits a hexagonal structure. The microstructure parameters (crystallite size, microstrain and dislocation density) were calculated for annealed films.Temperature dependence (300–500 K) of d.c. conductivity was studied for as-prepared and annealed thin films. The experimental results indicate that the electrical conduction taking place through thermally activated process. At higher temperatures, electrical conduction for as-prepared film is taking place in the extended states while localized states conduction in the band tails is most likely to take place for annealed films. Regarding the lower temperature range, conduction by hopping in the localized states near the Fermi level is found to be dominant. Thus, conductivity data in this range was analyzed using Mott's variable range hopping conduction, where Mott's parameters were calculated for SR-CdSe thin films.