Submicron focusing of XUV radiation from a laser plasma source using a multilayer Laue lens

The focusing properties of a one-dimensional multilayer Laue lens (MLL) were investigated using monochromatic soft X-ray radiation from a table-top, laser-produced plasma source. The MLL was fabricated by a focused ion beam (FIB) structuring of pulsed laser deposited ZrO₂/Ti multilayers. This novel method offers the potential to overcome limitations encountered in electron lithographic processes. Utilizing this multilayer Laue lens, a line focus of XUV radiation from a laser-induced plasma in a nitrogen gas puff target could be generated. The evaluated focal length is close to the designed value of 220 μm for the measurement wavelength of 2.88 nm. Divergence angle and beam waist diameter are measured by a moving knife edge and a far-field experiment, determining all relevant second-order moments based beam parameters. The waist diameter has been found to be approximately 370 nm (FWHM).     

磁控溅射制备的W,WSi2,Si单层膜和W/Si,WSi2/Si多层膜应力

采用直流磁控溅射技术制备了厚度约100 nm的W,WSi2,Si单层膜和周期约为20 nm,Si膜层厚度与周期的比值为0.5的W/Si,WSi2/Si周期多层膜.利用台阶仪对镀膜前后基底表面的面形进行了测试,计算并比较了不同膜系的应力值.结果表明:W单层膜表现出较大的压应力,而W/Si周期膜则表现为张应力.WSi2单层...     

自支撑二值化Beynon-Gabor波带片的制备及其单级聚焦特性

Gabor波带片是一种理想的单级聚焦光学元件,但制备困难.本文采用聚焦离子束直写技术成功制备出30环、20扇区的二值化Beynon-Gabor波带片,其有效面积半径为700μm,第一环半径90μm.利用各向异性腐蚀液对硅基底进行开孔,实现了Beynon-Gabor波带片二值化、自支撑、镂空的结构特征.在波长为355 nm的激光下测试其光学性能,结果表明所制备的Beynon-Gabor波带片主光轴上只存在1级衍射叠加后的焦点,不存在高级衍射焦点,具有优异的单级聚焦性能.     

XRD study on the effect of the deposition condition on pulsed laser deposition of ZnO films

Using a pulsed laser deposition (PLD) process on a ZnO target in an oxygen atmosphere, thin films of this material have been deposited on Si(111) substrates. An Nd: YAG pulsed laser with a wavelength of 1064 nm was used as the laser source. The influences of the deposition temperature, laser energy, annealing temperature and focus lens position on the crystallinity of ZnO films were analyzed by X-ray diffraction. The results show that the ZnO thin films obtained at the deposition temperature of 400°C and the laser energy of 250 mJ have the best crystalline quality in our experimental conditions. The ZnO thin films fabricated at substrate temperature 400°C were annealed at the temperatures from 400°C to 800°C in an atmosphere of N₂. The results show that crystalline quality has been improved by annealing, the optimum temperature being 600°C. The position of the focusing lens has a strong influence on pulsed laser deposition of the ZnO thin films and the optimum position is 59.5 cm from the target surface for optics with a focal length of 70 cm.      

Effect of 100 MeV O7+ ion beam irradiation on structural,optical and electronic properties of SnO2 thin films

In this paper, we present the impact of swift heavy ion beam irradiation on the structural, optical and electronic properties of SnO₂ thin films. Thin films were deposited using the pulsed laser deposition technique on Al₂O₃ substrates. Atomic force microscopy, X-ray diffraction, UV–visible absorption and temperature-dependent resistivity measurements were performed to explore the morphological, structural, optical and electronic properties of the as-deposited and irradiated samples. The peak intensity of the (200) peak was found to decrease monotonously with increasing irradiation fluence. The band gap energy of the 1×10¹¹ ion/cm² irradiated sample was found to increase. The electrical resistivity of the samples showed a continuous increase with the irradiation fluence.     

Microstructures and multiferroic properties of textured Bi0.8La0.2FeO3 thin films

La-substituted BiFeO₃, Bi_0.8La_0.2FeO₃, thin films were fabricated on Pt/Ti/SiO₂/Si substrates by pulsed laser deposition. X-ray diffraction and high-resolution transmission electron microscope were used to analyze the structures of the films. The results show the films fabricated under optimized growth condition are (0 1 2) textured. X-ray photoemission spectroscopy results indicate that the oxidation state of Fe ion is Fe³⁺ in the films without detectable Fe²⁺. The films show low leakage current and excellent dielectric characters. Multiferroic properties with a remnant ferroelectric polarization of 5.2 μC/cm² and a remanent magnetization of 0.02 μ_B/Fe were established. These results have some implications for further research.     

利用脉冲激光沉积技术在双轴织构的Ni基带上外延CeO2薄膜

利用脉冲激光沉积技术在氢还原气氛下成功地在双轴织构的Ni基带上外延了高质量的CeO₂薄膜. x射线衍射θ—２θ扫描和ω扫描结果表明，CeO₂薄膜在Ni基带上呈c轴方向生长，存在很强的平面外织构；极图和φ扫描显示它具有良好的平面内织构. Ni基片上织构的CeO₂薄膜为进一步在其上外延高质量的YBa₂Cu₃O_7-x超导薄膜提供了很好的模板. 关键词： 双轴织构的Ni基带 2薄膜')" href="#">CeO₂薄膜 脉冲激光沉积     

Characterization of ion beam sputter deposited W and Si films and W/Si interfaces by grazing incidence X-ray reflectivity, atomic force microscopy and spectroscopic ellipsometry

An ion beam sputtering system, which uses a commercial ECR microwave based plasma ion source, has been designed and fabricated in-house for deposition of soft X-ray multilayer mirrors. To begin with, in the ion beam sputtering system W, Si thin films, W/Si bi-layer and W/Si/W tri-layer samples have been deposited on c-Si substrates as precursors to W/Si multilayer stack. The samples have been characterized by grazing incidence X-ray reflectivity (GIXR), atomic force microscopy (AFM) and spectroscopic ellipsometry (SE) techniques. By analyzing the results, density, thickness, surface roughness of the single layer samples and interface width of the bi-layer and tri-layer samples have been estimated.     

Normal-incidence pulsed-laser deposition: better method for fabrication of multilayer structures

A new normal-incidence pulsed-laser deposition method is presented. Fe/Mn multilayers were fabricated using both 45°- and normal-incidence deposition of a pulsed laser and were characterized using the small-angle X-ray reflectivity measurement. This new method provides much better control of the lateral uniformity and layer thickness than the 45°-incidence deposition method.     

Laser conditioning and nonlinear absorption of LaF3/MgF2 dielectric multilayers at 193 nm

A sensitive and simple pulsed surface thermal lens (TL) technique is used in situ to investigate the laser conditioning and to measure the nonlinear absorption of LaF₃/MgF₂ dielectric multilayers deposited on CaF₂ substrates at 193 nm. Due to the high single-shot sensitivity of the surface TL technique, the laser conditioning can be monitored from the first shot of irradiation on a shot-by-shot basis. The LaF₃/MgF₂ multilayers show a very strong conditioning effect. The ratio of the absorption before and after the laser irradiation is in the range 4–8 for a highly reflective (LH)²⁰ LaF₃/MgF₂ multilayer, and 3–4 for (1L3H)⁷ and (3L1H)⁷ multilayers. In comparison, a (LH)²⁰ LaF₃/AlF₃ multilayer shows only a weak conditioning effect, with an absorption ratio of approximately 1.4. Our experimental results suggest that the strong conditioning effect of the LaF₃/MgF₂ multilayer is due to the absorption conditioning of the LaF₃ layers. However, the MgF₂ layers are shown to be responsible for the considerable increase in LaF₃ absorption as well as the ability to condition the absorption. The fluoride multilayers present non-negligible nonlinear absorption and the two-photon absorption coefficient of the multilayers is estimated to be approximately 5×10^-7 cm/W. Received: 11 December 2000 / Accepted: 20 February 2001 / Published online: 25 July 2001     

Characteristics of ZrC/ZrN and ZrC/TiN multilayers grown by pulsed laser deposition

ZrC/ZrN and ZrC/TiN multilayers were grown on (1 0 0) Si substrates at 300 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser. X-ray diffraction investigations showed that films were crystalline, the strain and grain size depending on the nature and pressure of the gas used during deposition. The elemental composition, analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), showed that films contained a low level of oxygen contamination. Simulations of the X-ray reflectivity (XRR) curves acquired from films indicated a smooth surface morphology, with roughness below 1 nm (rms) and densities very close to bulk values.Nanoindentation results showed that the ZrC/ZrN and ZrC/TiN multilayer samples exhibited hardness values between 30 and 33 GPa, slightly higher than the values of 28-30 GPa measured for pure ZrC, TiN and ZrN films.     

Fabrication of microelectrodes deeply embedded in LiNbO3 using a femtosecond laser

We present a novel technique to fabricate deeply embedded microelectrodes in LiNbO₃ using femtosecond pulsed laser ablation and selective electroless plating. The fabrication process mainly consists of four steps, which are (1) micromachining of microgrooves on the surface of LiNbO₃ by femtosecond laser ablation; (2) formation of AgNO₃ films on substrates; (3) scanning the femtosecond laser beam in the fabricated microgrooves for modification of the inner surfaces; and (4) electroless copper plating. The void-free electroless copper plating is obtained with appropriate cross section of microgrooves and uniform initiation of the autocatalytic deposition on the inner surface of grooves. The dimension and shape of the microelectrodes could be accurately controlled by changing the conditions of femtosecond laser ablation, which in turn can control the distribution of electric field inside LiNbO₃ crystal for various applications, opening up a new approach to fabricate three-dimensional integrated electro-optic devices.     

13.9nm软X射线激光用大面积多层膜分束镜研制

 基于分束镜反射率和透射率的乘积为衡量标准的原则,设计了13.9nm软X射线激光干涉测量所需的多层膜分束镜，用磁控溅射法在有效面积达10mm×10mm，厚100nm的氮化硅窗口上镀制Mo/Si多层膜,实现了分束镜制作。用表面轮廓仪实测分束镜面形精度达到nm量级，同步辐射反射率计测试表明,分束镜的反射率和透射率乘积约4%。     

X射线布拉格-菲涅耳光学元件的实验研究

用光学全息方法在涂有光刻胶的多层膜表面上的形成布拉格－菲涅耳元件所需的波带片图形,通过离子束刻蚀方法将波带片图形转写到多层膜上,完成元件的制作,给出布拉格－菲涅耳光学元件测量结果,测量结果表明上述方法适于制作布拉格－菲涅耳元件。     

Specific character of the 119Sn thin films growth on amorphous Si by the CBPLD method

The research of the ¹¹⁹Sn thin films growth on amorphous Si that is important for the multilayer periodical spin-tunnel nanostructures creation have been investigated in this paper. The ¹¹⁹Sn mono-isotopic thin films on the silicon substrates (100) had been received by crossed-beam pulsed laser deposition method (CBPLD). Similarly the [Fe/Si/Sn/Si] multilayer periodical structures have been deposited. The received samples were investigated by atomic-force microscopy, electronic microscopy and X-ray reflectometry methods. It has been established that at ¹¹⁹Sn film thickness up to 3 nm it is possible to received atomic-smooth surfaces with 0.5 nm roughness.     

Wear resistance of ZrC/TiN and ZrC/ZrN thin multilayers grown by pulsed laser deposition

ZrC/TiN and ZrC/ZrN multilayers thinner than 350 nm were grown on (100) Si substrates at a temperature of 300 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser (λ=248 nm, pulse duration τ=25 ns, 8.0 J/cm² fluence and 40 Hz repetition rate). Cross-sectional transmission electron microscopy, Auger electron spectroscopy depth profiling and simulations of X-ray reflectivity curves indicated that there was intermixing between the deposited layers at the interfaces as well as between the first layer and the substrate. Nanoindentation investigations found hardness values between 35 and 38 GPa for the deposited multilayers. Linear unidirectional sliding wear tests were conducted using a ball-on-plate tribometer under 1 N normal force. Wear tracks were produced in a Hysitron nanoindenter with 1 μm radius diamond tip under a 500 μN load. High-resolution cross-sectional transmission electron microscopy studies of the wear tracks showed that the multilayers withstood these tests without significant damage. The results could be explained by the use of a high laser fluence during deposition that resulted in very dense and strongly adherent nanocrystalline layers.     

软X射线相位型聚焦波带片的研制

软X射线波带片是软X射线光学中聚焦、色散和成像的重要元件。以激光全息-离子束刻蚀技术制作金的振幅型软X射线聚焦波带片,以此为掩模,利用接触式同步辐射光刻和离子束刻蚀技术在聚酰亚胺衬底上,分别制作出了镍和锗的软X射线相位型聚焦波带片。     

Controllable microstructures and multiferroic properties of Pb(Zr0.53Ti0.47)O3-CoFe2O4 composite films

1-3 and 2-2 types Pb(Zr_0.53Ti_0.47)O₃-CoFe₂O₄ (PZT-CFO) composite films with controllable microstructures, consisted by CFO nanopillar embedded in PZT matrix and PZT-CFO gratings respectively, have been fabricated on Pt/Ti/SiO₂/Si substrates by combining lithography technology and pulsed laser deposition. X-ray diffraction confirms that the films are well crystallized under optimized postannealing conditions. Scanning electron microscope reveals that the periodic microstructures can be well controlled. Especially, intrinsic room temperature ferroelectric and ferrimagnetic behaviors are observed simultaneously. The structure-properties relationship is discussed. Our results may provide an alternative method to design and prepare multiferroic composite films with controllable microstructures.     

Influence of deposition conditions on the microstructure of oxides thin films

Thin films of ZrO₂, HfO₂ and TiO₂ were deposited on kinds of substrates by electron beam evaporation (EB), ion assisted deposition (IAD) and dual ion beam sputtering (DIBS). Then some of them were annealed at different temperatures. X-ray diffraction (XRD) was applied to determine the crystalline phase and the grain size of these films, and the results revealed that their microstructures strongly depended on the deposition conditions such as substrate, deposition temperature, deposition method and annealing temperature. Theory of crystal growth and migratory diffusion were applied to explain the difference of crystalline structures between these thin films deposited and treated under various conditions.     

Substrate dependent transport and magnetotransport in manganite multilayer

We report magnetotransport properties of La_0.5Pr_0.2Sr_0.3MnO₃ (LPSMO) {5 layers}/La_0.5Pr_0.2Ba_0.3MnO₃ (LPBMO) {4 layers} manganite multilayers grown on single crystalline STO (h 0 0) and NGO (h 0 0) substrates using pulsed laser deposition (PLD) technique. An appreciable magnetoresistance (MR) ∼56% (80 kOe field) at room temperature (RT) is exhibited by the heterostructure deposited on STO substrate having field coefficient of resistance (FCR) ∼35% (100 Oe) while the multilayer deposited on NGO substrate exhibits MR∼61% (80 kOe field) and FCR∼18% (5 kOe) at RT. The observed values of temperature coefficient of resistance (TCR) are ∼3.15% and 2.77% at RT for the multilayers grown on STO and NGO substrates, respectively. A comparison of the field sensitivity of the multilayered structure studied with those reported for LPSMO/Al₂O₃/LPSMO (FCR∼20% at 220 K) and LPSMO/STO film (FCR∼13% at 250 K) shows that the multilayer exhibits higher field sensitivity, which can be attributed to the improved LPSMO-LPBMO interfaces. In this communication, the results of the structural, transport and magnetotransport studies on LPSMO/LPBMO multilayered systems have been discussed.