Microstructure and strain analysis of GaN epitaxial films using in-plane grazing incidence x-ray diffraction

This paper investigates the major structural parameters, such as crystal quality and strain state of （001）-oriented GaN thin films grown on sapphire substrates by metalorganic chemical vapour deposition, using an in-plane grazing incidence x-ray diffraction technique. The results are analysed and compared with a complementary out-of-plane x- ray diffraction technique. The twist of the GaN mosaic structure is determined through the direct grazing incidence t of （100） reflection which agrees well with the result obtained by extrapolation method. The method for directly determining the in-plane lattice parameters of the GaN layers is also presented. Combined with the biaxial strain model, it derives the lattice parameters corresponding to fully relaxed GaN films. The GaN epilayers show an increasing residual compressive stress with increasing layer thickness when the two dimensional growth stage is established, reaching to a maximum level of-0.89 GPa.

Nested grazing incidence optics for x ray detection

Grazing incidence optics （GIO） is the most important compound in an x-ray detection system; it is used to concentrate the x-ray photons from outer space. A nested planar GIO for x-ray concentration is designed and developed by authors in this paper; planar segments are used as the reflection mirror instead of curved segments because of the simple process and low cost. After the complex assembling process with a special metal supporter, a final circle light spot of φ 12 mm was obtained in the visible light testing experiment of GIO; the effective area of 1710.51 mm^2@ 1 keV and 530 mm^2@8 keV is obtained in the x-ray testing experiment with the GIO-SDD combination, which is supposed to be a concentrating detector in xray detection systems.

Modification of Classical SPM for Slightly Rough Surface Scattering with Low Grazing Angle Incidence

Based on the impedance/admittance rough boundaries, the reflection coefficients and the scattering cross section with low grazing angle incidence are obtained for both VV and HH polarizations. The error of the classical perturbation method at grazing angle is overcome for the vertical polarization at a rough Neumann boundary of infinite extent. The derivation of the formulae and the numerical results show that the backscattering cross section depends on the grazing angle to the fourth power for both Neumann and Dirichlet boundary conditions with low grazing angle incidence. Our results can reduce to that of the classical small perturbation method by neglecting the Neumann and Dirichlet boundary conditions.

Glancing incidence x-ray fluorescence spectrometry based on a single-bounce parabolic capillary

Glancing incidence x-ray fluorescence spectrometry using a single-bounce parabolic capillary is proposed for the analysis of layered samples.The divergence of the x-ray beam was 0.33 mrad.In this paper,we used this instrumental setup to analyze a Si single crystal and a 50 nm HfO_(2) single-layer film deposited on a Si substrate.

In-situ temperature-controllable grazing incidence X-ray scattering of semiconducting polymer thin films under stretching

The advancement in grazing incidence X-ray scattering(GIWAXS)techniques at synchrotron radiation facilities has significantly deepened our understanding of semiconducting polymers.However,investigation of ultrathin polymer films under tensile conditions poses challenge,primarily due to limitations associated with the lack of suitable sample preparation methods and new stretching devices.This study addresses these limitations by designing and developing an in-situ temperature-controllable stretching sample stage,which enables real-time structural measurements of ultrathin polymer films at Beijing Synchrotron Radiation Facility.In particular,we report,for the first time,in-situ GIWAXS results of representative semiconducting polymer thin films under variable-temperature stretching.This research has overcome the limitations imposed by sample constraints,thus facilitating the achievement of valuable insights into the behavior of ultrathin polymer films under tensile conditions.Distinct changes in the molecular ordering and packing within the polymer thin films as a result of increasing applied strain and temperature have been uncovered.This study promotes future developments in the field,thus enabling the design and optimization of intrinsically stretchable electronic devices and other technologically relevant applications.

Hard X-ray focusing resolution and efficiency test with a thickness correction multilayer Laue lens

The multilayer Laue lens(MLL) is a diffractive focusing optical element which can focus hard X-rays down to the nanometer scale. In this study, a WSi_(2)/Si multilayer structure consisting of 1736 layers, with a 7.2-nm-thick outermost layer and a total thickness of 17 μm, is prepared by DC magnetron sputtering. Regarding the thin film growth rate calibration, we correct the long-term growth rate drift from 2 to 0.6%, as measured by the grazing incidence X-ray reflectivity(GIXRR). A one-dimensional line focusing resolution of 64 nm was achieved,while the diffraction efficiency was 38% of the-1 order of the MLL Shanghai Synchrotron Radiation Facility(SSRF) with the BL15U beamline.

Small angle X-ray scattering beamline at SSRF

Beamline BL16B1 at Shanghai Synchrotron Radiation Facility(SSRF) is dedicated to studying the microstructure and dynamic processes of polymers, nanomaterials, mesoporous materials, colloids, liquid crystals,metal materials, etc. At present, SAXS, wide angle X-ray scattering(WAXS), simultaneous SAXS/WAXS,grazing incident SAXS, and anomalous SAXS techniques are available for end user to conduct diverse experiments at this beamline. The sample-to-detector distance is adjustable from 0.2 m to 5 m. The practicable q-range is 0.03–3.6 nm-1at incident X-ray of 10 ke V for conventional SAXS whilst a continuous q-region of0.06–33 nm-1can be achieved in simultaneous SAXS/WAXS mode. Time-resolved SAXS measurements in sub-second level was achieved by the beamline upgrating in 2013. This paper gives detailed descriptions about the status, performance and applications of the SAXS beamline.

Evaluation of both composition and strain distributions in InGaN epitaxial film using x-ray diffraction techniques

The composition and stain distributions in the InGaN epitaxial films are jointly measured by employing various x-ray diffraction （XRD） techniques, including out-of-plane XRD at special planes, in-plane grazing incidence XRD, and reciprocal space mapping （RSM）. It is confirmed that the measurement of （204） reflection allows a rapid access to estimate the composition without considering the influence of biaxial strain. The two-dimensional RSM checks composition and degree of strain relaxation jointly, revealing an inhomogeneous strain distribution profile along the growth direction. As the film thickness increases from 100 nm to 450 nm, the strain status of InGaN films gradually transfers from almost fully strained to fully relaxed state and then more In atoms incorporate into the film, while the near-interface region of InGaN films remains pseudomorphic to GaN.

Numerical study of the Ne-like Cr x-ray laser at 28.6nm

We investigate the Ne-like Cr x-ray laser at 28.6 nm by using a modified ID lagrangian hydrodynamic code MEDI03 coupled with an atomic physics data package and a 2D ray tracing code as a post-processor. The laser pumping configuration includes two prepulses and one main pulse. The first prepulse normally irradiates the target, while the second prepulse and the main pulse irradiate the target at grazing-incident angles. We predict that saturation can be achieved for the Ne-like Cr x-ray lasers with a total pumping energy of 125mJ, Good beam qualities with no deflecting angle and a small divergence angle of 5 mrad are observed.

Neutralization process of Xe^q＋ ion grazing on Al（111） surface

A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q＋ on Al（111） surface as a function of the incidence angle, energy and charge state is also studied.

In situ grazing-incidence small-angle X-ray scattering observation of block-copolymer templated formation of magnetic nanodot arrays and their magnetic properties

The fabrication of bit-patterned media （BPM） is crucial for new types of hard disk drives. The development of methods for the production of BPM is progressing rapidly. Conventional lithography reaches the limit regarding lateral resolution, and new routes are needed. In this study, we mainly focus on the dependence of the size and shape of magnetic nanodots on the Ar＋-ion etching duration, using silica dots as masks. Two-dimensional （2D） arrays of magnetic nanostructures are created using silica-filled diblock-copolymer micelles as templates. After the self-assembly of the micelles into 2D hexagonal arrays, the polymer shell is removed, and the SiO2 cores are utilized to transform the morphology into a （Co/Pt）2-multilayer via ion etching under normal incidence. The number of preparation steps is kept as low as possible to simplify the formation of the nanostructure arrays. High-resolution in situ grazing-incidence small-angle X-ray scattering （GISAXS） investigations are performed during the Ar＋-ion etching to monitor and control the fabrication process. The in situ investigation provides information on how the etching conditions can be improved for further ex situ experiments. The GISAXS patterns are compared with simulations. We observe that the dots change in shape from cylindrical to conical during the etching process. The magnetic behavior is studied by utilizing the magneto-optic Kerr effect. The Co/Pt dots exhibit different magnetic behaviors depending on their size, interparticle distance, and etching time. They show ferromagnetism with an easy axis of magnetization perpendicular to the film. A systematic dependence of the coercivitv on the dot size is observed.

Theoretical Investigation of X-Ray Absorption near Edge Spectroscopy (XANES) Angular Dependence of Aligned Carbon Nanotubes Grown by DC HF CVD Process

Carbon nanotubes (CNTs) grown on plain substrates SiO2/Si(100) by a direct current and hot filaments catalytic chemical vapor deposition process have been studied by synchrotron X-ray absorption near edge spectroscopy (XANES) technique to theoretically investigate the angular-dependence of carbone (C) K-edge π* and σ* transitions. Experimental XANES spectra show that π* resonance increases with the incidence angle from normal to grazing incidence angle while σ* resonance decreases. This has been explained by the sine-square and cosine-square dependencies of π* and σ* intensities, respectively. These results were confirmed by theoretical XANES curves of highly oriented pyrolytic graphite (HOPG) and CNTs plotted versus incidence angle. It has been shown that π* and σ* transitions strongly depend on the nature of polarized light (linearly or circularly). At the linear polarized light, π* resonance is a preference as well as at right-circular polarized. At the left-circular polarized light, σ* resonance is a preference. The π* intensities are high at parallel orientation and the σ* intensities are low at normal orientation. The smallest π* intensity is noticed at normal orientation, where the π* orbitals are supposed to be lying parallel to the surface plane for perfectly aligned HOPG or CNTs. This explains the incomplete extinction of π* intensity. We noticed at parallel orientation a region where any π* and σ* transitions did not expect because of the lack of polarization light.

超声波干涉及可视化实验装置研制

为了丰富大学物理声学实验内容,研制了一种多功能超声波干涉实验装置。基于空气介质设计了双振子干涉声速测量实验和半波损失验证实验。分别采用干涉声场测量法和干涉条纹移动法进行声速测量实验,并利用示波器实现了干涉声场声压分布的可视化。分别以有机玻璃、橡胶和玻璃为反射面材料,利用干涉法验证掠入射条件下的半波损失现象,并估算出掠入射角的范围。该实验装置实验现象明显、可操作性强,获评北京市第十六届大学生物理实验竞赛一等奖。

溶液法原位大面积制备钙钛矿光电薄膜成膜的同步辐射可视化结晶过程研究

溶液法是新型光电器件制备的重要手段,然而以钙钛矿半导体材料为代表的薄膜样品制备通常需要在手套箱环境下完成,传统的实验表征大多在空气环境下进行,这显然很难反映薄膜结构与器件性能间的真实关联,因此急需对溶液成膜过程的微结构演变开展原位实时研究.为了实现溶液法成膜中的结构与形貌的同步辐射掠入射广角散射实时观测,本文结合上海同步辐射光源线站布局,报道了一种基于手套箱的原位成膜观测装置,可实现标准手套箱环境(c(H_(2)O,O_(2))<1×10^(-6))下远程控制薄膜旋涂、涂布及样品后处理,并实时可视化监测微结构和形貌演变.基于该装置进行的钙钛矿薄膜狭缝涂布大面积成膜结晶过程的原位GIWAXS/GISAXS(gtrazing incidence wide and small angle X-ray scattering)可视化测试揭示了薄膜微结构转变的内在驱动力:钙钛矿薄膜沉积界面层的优化对提升钙钛矿成核速率、诱导结晶择优取向、形成晶粒有序堆叠等具有“共性作用”,同时在成膜过程中的新生中间相显著提升软晶格薄膜质量和稳定性.基于各层均采用卷对卷全溶液狭缝涂布方法制备的大面积全柔性三维钙钛矿薄膜太阳能电池转换效率提升至5.23%(单个器件面积约15 cm^(2)),为迄今报道的这一体系该尺寸的全溶液狭缝涂布柔性钙钛矿器件的最高器件效率之一.因而,基于该同步辐射原位GIWAXS/S/GISAXS装置可以获得控制薄膜生长界面特性和薄膜品质的关键工艺,指导优化制备薄膜的最佳工艺条件.

7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier

To obtain short pulse width and high peak power laser, a 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this Letter. We use a compact side-pumped Nd∶YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, and the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356 mm × 226 mm × 84 mm and may be used for applications such as laser altimeters and ladar systems.

黄芪多糖对贵乾半细毛羊疾病发生、生长性能及生化指标的影响

为研究黄芪多糖对放牧贵乾半细毛羊疾病发生率、生长性能及生理生化指标的影响,试验选择健康、体重相近的6月龄贵乾半细毛羊120只,随机分为对照组、试验A组、B组、C组,每组30只,每组3个重复,每个重复10只。对照组日粮中不添加黄芪多糖,试验A组、B组和C组分别在日粮中添加1、2、3 g/(d·只)黄芪多糖。预饲期15 d,试验期90 d,观察疾病发生,测定各组羊只的生长性能并采集血液检测生理生化指标。结果表明:(1)试验C组发病率最低(3.33%)对照组发病率最高(26.67%)。(2)C组平均日增重极显著高于对照组(P<0.01),显著高于试验B组和C组(P<0.05);且对照组日精料采食量显著低于试验组(P<0.05)。(3)C组抗氧化指标SOD和GSH-Px显著高于对照组(P<0.05)。(4)C组的GPT指标显著高于对照组(P<0.05)。综上,日粮中添加黄芪多糖可提高放牧贵乾半细毛羊日增重,提高机体免疫能力和抗氧化力。

Characterization of lattice parameters gradient of Cu(In1-xGax)Se2 absorbing layer in thin-film solar cell by glancing incidence X-ray diffraction technique

In or Ga gradients in the Cu(In1-xGax)Se2(CIGS)absorbing layer lead to change the lattice parameters of the absorbing layer,giving rise to the bandgap grading in the absorbing layer which is directly associated with the degree of absorbing ability of the CIGS solar cell.We tried to characterize the depth profile of the lattice parameters of the CIGS absorbing layer using a glancing incidence X-ray diffraction(GIXRD)technique,and then investigate the bandgap grading of the CIGS absorbing layer.When the glancing incident angle increased from 0.50 to 5.00°,the a and c lattice parameters of the CIGS absorbing layer gradually decreased from 5.7776(3)to 5.6905(2)?,and 11.3917(3)to 11.2114(2)?,respectively.The depth profile of the lattice parameters as a function of the incident angle was consistent with vertical variation in the compositionof In or Ga with depth in the absorbing layer.The variation of the lattice parameters was due to the difference between the ionic radius of In and Ga co-occupying at the same crystallographic site.According to the results of the depth profile of the refined parameters using GIXRD data,the bandgap of the CIGS absorber layer was graded over a range of 1.222-1.532 eV.This approach allows to determine the In or Ga gradients in the CIGS absorbing layer,and to nondestructively guess the bandgap depth profile through the refinement of the lattice parameters using GIXRD data on the assumption that the changes of the lattice parameters or unit-cell volume follow a good approximation to Vegard’s law.

可变入射距离平焦场谱仪的概念设计

从理论上证明了可变入射距离的平焦场软Ｘ射线谱仪设计的可行性。对于标称栅距σ０＝（１／１２００）ｍｍ和象差修正项Ｍ２０＝－２０／Ｒ，Ｒ分别为５６４９和６０００ｍｍ的光栅，对不同的入射距离，计算出与平焦场相对应的入射角和成象距离，使一定波长范围内的光谱可以被聚焦在一个平面上，从而提高了变栅距光栅使用的灵活性。同时可通过取消谱仪中入射狭缝，使谱仪的光通量提高约１个量级。

多层嵌套掠入射光学系统研制及在轨性能评价

大探测面积、提高探测器灵敏度方面发挥着重要作用,实现了国内首次在轨验证.针对脉冲星导航探测X射线光子到达时间的特点,开展了基于单次抛物面镜反射的掠入射聚焦光学系统设计,通过理论计算与推导,获得了可制造的光学系统反射镜设计参数,光学系统理论有效面积为15.6 cm2@1 keV,对设计的光学系统进行了聚焦性能仿真,全视场范围内均满足探测器聚焦要求,开展电铸镍复制工艺研究,完成了芯轴的超精密控形加工,在此基础上制造了4层金属反射镜,利用北京同步辐射4B7B光束线测试了各层反射镜的反射率,基于实测反射率的光学系统有效面积为13.2 cm2@1 keV.最后基于在轨观测数据,评价得到光学系统的有效面积为4.22 cm2@1 keV,分析了地面标定有效面积与在轨评价有效面积存在差别的原因,验证了设计、仿真与制造方法的正确性,为大面积掠入射光学系统的研制奠定了基础.

激光原型装置KBAX射线显微镜网格测试

利用光线追迹的方法模拟了KBA显微镜成像,确定了光轴的方向并计算了KBA显微镜的几何调制传递函数。根据KBA模拟光路,提出了利用可见光作为模拟KBAX射线显微镜的光轴在激光原型装置上的瞄准和安装的方法,该方法掠入射角的调节精度为0.25°。利用周期为20μm的Ni网格在激光原型装置上对KBA显微镜进行了X射线成像实验,用X射线CCD记录图像,获得了较清晰的网格图像。