Composition spread metal thin film fabrication technique based on ion beam sputter deposition

A composition spread metal thin film fabrication technique based on ion beam sputter deposition method was developed. The technique enables us to fabricate any desired part or a complete binary/ternary composition spread metal thin films onto a single substrate by sequentially sputtering different target materials. Composition spread metal thin films can be deposited directly on a dielectric film in patterned electrode shape for C-V and I-V measurements. The system could be especially useful in the search for new multi-component metal gate materials.     

Pulsed laser deposition of multiwalled carbon nanotubes thin films

The physical/chemical properties of multiwalled carbon nanotubes have attracted much interest for applications in different fields, from micro-electronic to coating technology due, in particular, to their peculiar conductivity properties, to their hardness and high resistance to thermal stress. The technology to produce carbon nanotubes thin films with the desired properties, however, is still under development. In this work, we report on multiwalled carbon nanotubes thin films deposited by pulsed laser deposition techniques ablating commercially polystyrene-nanotubes pellets on alumina substrates. MicroRaman spectroscopy and high resolution Transmission Electron Microscopy provide the experimental confirmation that carbon nanotubes-like structures are present on the alumina surface with both minimal morphological damage of the tubes and structural changes induced by laser beam.     

环境友好半导体Mg2Si薄膜的研究进展

介绍了近年来Mg2Si薄膜的研究进展。从Mg2Si材料的晶体结构出发,重点对Mg2Si薄膜的基本性质、制备方法和应用前景进行了论述。研究表明,Mg2Si是一种窄带隙间接半导体材料,在光电和热电领域都具有较好的应用价值,因其兼具了组成元素地层含量丰富、无毒、无污染等优点,被视为是一种新型的环境友好半导体材料。在Mg2Si薄膜的外延生长技术方面,目前比较成熟的方法有分子束外延、脉冲激光沉积、反应扩散等多种,但普遍存在制备条件较苛刻,成膜质量不高等缺点。最后,对目前存在的问题及未来的研究动向做了简要讨论。     

慢正电子束流技术在金属/合金微观缺陷研究中的应用

正电子湮没谱学技术是研究材料微观结构非常有效的一种核谱学分析方法, 主要用于获取材料内部微观结构的分布信息, 特别是微观缺陷结构及其特性等传统表征方法难以获取的微观结构信息. 近年来, 在慢正电子束流技术快速发展的基础上, 正电子湮没谱学技术在薄膜材料表面和界面微观结构的研究中得到了广泛应用. 特别是该技术对空位型缺陷的高灵敏表征能力, 使其在金属/合金材料表面微观缺陷的形成机理、缺陷结构特性及其演化行为等研究方面具有独特的优势. 针对材料内部微观缺陷的形成、演化机理以及缺陷特性的研究, 如缺陷的微观结构、化学环境、电子密度和动量分布等, 正电子湮没谱学测量方法和表征分析技术已经发展成熟. 而能量连续可调的低能正电子束流, 进一步实现了薄膜材料表面微观结构深度分布信息的实验表征. 本文综述了慢正电子束流技术应用研究的最新进展, 主要围绕北京慢正电子束流装置在金属/合金材料微观缺陷的研究中对微观缺陷特性的表征和表面微观缺陷演化行为的应用研究成果展开论述.     

Investigation of the coercive force of thin magnetic films obtained by vacuum sputtering

The investigation of the magnetic properties of thin magnetic films is of great scientific as well as practical interest for two reasons. First, thin magnetic films, being two dimensional (one of the dimensions is much smaller than the others) show novel properties; their study can solve various problems in the theory of ferromagnetism which are difficult to solve using only data obtained from bulk materials [1,2]. Second, scientific and practical interest with respect to thin magnetic films has increased due to their possible practical applications for logic and memory elements in computer technology [3–7].Their coercive force, which is relatively increased with respect to bulk magnetic materials, is one of the basic properties of thin magnetic films. As is known, the coercive force of thin magnetic films is one of the most important design parameters for memory and logic elements in computer technology, since the coercive force defines the current necessary for the reversal of the magnetic polarity. Although this parameter is of great importance and intensive investigations of it have been carried out, precise data do not yet exist. As a matter of fact, the existing data are often contradictory, because basic technological factors were not taken into account in the investigations.To illustrate the above we give the results of a number of experimental studies in which attempts were made to establish the dependence of the coercive force upon the thickness of the magnetic film as shown in Fig. 1 (curves 2,3,4,7,15,17). Curve 16 is a calculated curve, the other curves refer to thin magnetic films obtained by various authors using the electrolytic depositing method.From this data it is evident that the magnitude of the coercive force for a certain thickness of thin magnetic film, prepared from the same magnetic material according to the same method, assumes different values with different authors. This is explained by the fact that the investigation of the dependence of the coercive force upon the film thickness is extremely complex because it is difficult to control the basic technological factors and also because various additional factors come into play which were not taken into account by the authors.     

Investigation of interface roughness cross-correlation properties of optical thin films from total scattering losses

The interface roughness and interface roughness cross-correlation properties affect the scattering losses of high-quality optical thin films. In this paper, the theoretical models of light scattering induced by surface and interface roughness of optical thin films are concisely presented. Furthermore, influence of interface roughness cross-correlation properties to light scattering is analyzed by total scattering losses. Moreover, single-layer TiO₂ thin film thickness, substrate roughness of K9 glass and ion beam assisted deposition (IBAD) technique effect on interface roughness cross-correlation properties are studied by experiments, respectively. A 17-layer dielectric quarter-wave high reflection multilayer is analyzed by total scattering losses. The results show that the interface roughness cross-correlation properties depend on TiO₂ thin film thickness, substrate roughness and deposition technique. The interface roughness cross-correlation properties decrease with the increase of film thickness or the decrease of substrates roughness. Furthermore, ion beam assisted deposition technique can increase the interface roughness cross-correlation properties of optical thin films. The measured total scattering losses of 17-layer dielectric quarter-wave high reflection multilayer deposited with IBAD indicate that completely correlated interface model can be observed, when substrate roughness is about 2.84 nm.     

Miniature electron bombardment evaporation source: evaporation rate measurement

Miniature electron beam evaporation sources which operate on the principle of vaporization of source material, in the form of a tip, by electron bombardment are produced by several companies specialised in UHV equipment. These sources are used primarily for materials that are normally difficult to deposit due to their high evaporation temperature. They are appropriate for special applications, like heteroepitaxial thin films growth that require very low and well controlled deposition rate. We propose a simple and easily applicable method of evaporation rate control. The method is based on the measurement of ion current produced by electron bombardment of evaporated atoms. In order to be able to determine the ion current – evaporation flux calibration curves we measured the absolute values of evaporation flux by means of Bayard-Alpert ion gauge.     

束晕-混沌的复杂性理论与控制方法及其应用前景

本文系统论述涉及强流加速器等强流离子束装置中产生的束晕-混沌的复杂性理论与控制方法及其应用前景。强流离子束在核材料生产与增殖、洁净核能、放射性废物嬗变、放射性药物生产、重离子聚变、高能物理、核科学与工程、国防与民用工业和医疗等许多方面都有极其重要的应用潜力和诱人的发展前景。尤其是，近年来强流加速器驱动的放射性洁净核能系统是国内外关注的热门课题，因为它比常规核电更安全、更干净、更便宜。但是，强流离子束形成的束晕-混沌的复杂性现象已引起了国内外广泛关注，需要加以抑制、控制和消除这类现象，解决这一难题已经成为强流离子束应用中的关键问题之一。目前不仅必须深入研究这类束晕-混沌的复杂特性及其产生的物理机制，而且需要研究如何实现对束晕-混沌的有效控制，并寻求和发展其新理论、新方法和新技术。这就向强流离子束物理和非线性-复杂性科学及其技术提出了一系列极富挑战性的新课题。本文结合国内外的研究概况，根据我们多年来的研究成果，特别是我们首创性地提出了一些束晕-混沌的有效控制方法，它们包括：非线性反馈控制法，小波反馈控制法，变结构控制法，延迟反馈控制法，参数自适应控制法等，进行重点的介绍。对上述课题当前的主要进展及相关问题进行系统的总结和比较全面综述的评论。最后，指出该领域今后的研究方向，以推动这个崭新领域的深入研究和应用发展。     

电子束蒸发和离子束溅射HfO_2紫外光学薄膜

HfO2薄膜在紫外光学中具有十分重要的地位,不同方法制备的HfO2薄膜特性不同,可以满足不同的实际应用需求。本文分别利用电子束蒸发和离子束溅射方法制备了用于紫外光区域的HfO2薄膜,并对薄膜的材料和光学特性进行了表征与比较。通过对单层HfO2薄膜的实测透射和反射光谱进行数值反演,得到了HfO2薄膜在230～800 nm波段的折射率和消光系数色散曲线,结果表明两种方法制备的HfO2薄膜在250nm的消光系数均小于2×10-3。在此基础上,制备了两种典型的紫外光学薄膜元件(紫外低通滤波器和240nm高反射镜),其光谱性能测试结果表明,两种不同方法制备的器件均具有较好的光学特性。     

溅射粒子能量对金属Mo薄膜表面特性的影响

利用原子力显微镜研究了不同溅射离子能量对Mo薄膜表面形貌的影响.利用特殊设计的夹具，在同一真空内完成所有薄膜样品的制备，减少了多次沉积过程对薄膜生长特性的影响 .对原子力显微镜测量得到的表面高度数据进行相关运算，从统计角度定量地研究了不同沉积能量下Mo薄膜表面特性.结果表明，薄膜表面具有典型的分形特征，在相关运算的基础上给出表面的分形维数、水平相关长度、界面宽度等参数.其中，屏栅电压为500V时制备 的薄膜样品与300和700?V时制备的薄膜样品表面的界面宽度及水平相关长度具有倍数差别，但三种溅射电压下薄 关键词： 离子束溅射 钼 薄膜 分形     

沉积工艺对二氧化锆薄膜生长特性影响的研究

利用反应离子束溅射、反应磁控溅射和电子束蒸发在K9基底上沉积ZrO2薄膜，并用原子力显微镜对薄膜表面形貌进行测量。通过数值相关运算，对不同工艺条件下薄膜生长界面进行定量描述，得到了薄膜表面的粗糙度指数、横向相关长度、标准偏差粗糙度等参量。由于沉积条件的不同，薄膜生长具有不同的动力学过程。在反应离子束溅射和反应磁控溅射沉积薄膜过程中，薄膜生长动力学行为均可用Kuramoto-Sivashinsky方程来描述，电子束蒸发制备薄膜的过程可以用Mullins扩散模型来描述，并发现在沉积薄膜过程中基底温度和沉积过程的稳定性对薄膜表面特征影响很大。     

Characterisation of nickel silicide thin films by spectroscopy and microscopy techniques

This article discusses the formation and detailed materials characterisation of nickel silicide thin films. Nickel silicide thin films have been formed by thermally reacting electron beam evaporated thin films of nickel with silicon. The nickel silicide thin films have been analysed using Auger electron spectroscopy (AES) depth profiles, secondary ion mass spectrometry (SIMS), and Rutherford backscattering spectroscopy (RBS). The AES depth profile shows a uniform NiSi film, with a composition of 49-50% nickel and 51-50% silicon. No oxygen contamination either on the surface or at the silicide-silicon interface was observed. The SIMS depth profile confirms the existence of a uniform film, with no traces of oxygen contamination. RBS results indicate a nickel silicide layer of 114 nm, with the simulated spectra in close agreement with the experimental data. Atomic force microscopy and transmission electron microscopy have been used to study the morphology of the nickel silicide thin films. The average grain size and average surface roughness of these films was found to be 30-50 and 0.67 nm, respectively. The film surface has also been studied using Kikuchi patterns obtained by electron backscatter detection.     

有机分子束外延技术与研究进展

本文介绍了超高真空分子束外延生长有机薄膜的技术及其研究进展 ,讨论了外延材料的纯化过程和杂质对外延薄膜结构的影响 ;从理论和实验观点评论了薄膜的生长性质和膜的有序结构。超高真空有机分子束外延技术是一种多用途的高技术 ,可以生长有机、无机、有机 /无机混和的薄膜结构。这种薄膜结构是未来光学和电子器件有希望应用的新一类工程材料。     

有机分子束外延技术与研究进展

本介绍了超高真空分子束外延生长有机薄膜的技术及基研究进展,讨论了外延材料的纯化过程和杂质对外延薄膜的影响;从理论和实验观点评论了薄膜的生长性质和膜的有序结构。超高真空有机分子束外延技术是一种多用途的高技术,可以生长有机、无机、有机／无机混和的薄膜结构。这种薄膜结构是示来光学和电子器件有希望应用的新一类工程材料。     

Formation,Dynamics, and Characterization of Nanostructures by Ion Beam Irradiation

Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (～10^?12 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of materials or for its characterization. The synthesis of nanostructures, and their modification by ion beam technique will be discussed in this review article. Formation of nanostructures using ion beam technique will be discussed first. Depending on species (e.g., mass and charge state) and energy range, there are various modes for an energetic ion to dissipate its energy. The role of the electron will also be covered in this article as a basic principle of its interaction with matter, which is same as for an ion. By using a simple reactive ion beam or electron induced deposition, a secondary phase can be nucleated by ion beam mixing techniques, either by using inert gas irradiation or reactive gas implantation on any desired substrate. Nucleation of secondary phase can also be executed by electron irradiation and direct implantation of either negative or positive ions. Post implantation annealing processes are required for the complete growth of clusters formed in most of these ion irradiation techniques. Implantation processes being inherently a non-equilibrium technique, defects always have a role to play in phase formation, amorphization, and beyond (blister formation). When implanted with large energy, even electrons, one of the lightest charged particles, also manifest these properties. Electronic and nuclear energy losses of the impinging charged particle play a crucial role in material modification. Doping a nanocluster, however, is still a controversial topic. Some light will be shed on this topic with a discussion of focused ion beam.     

The growth and modification of materials via ion–surface processing

A wide variety of gas phase ions with kinetic energies from 1–10⁷ eV increasingly are being used for the growth and modification of state-of-the-art material interfaces. Ions can be used to deposit thin films; expose fresh interfaces by sputtering; grow mixed interface layers from ions, ambient neutrals, and/or surface atoms; modify the phases of interfaces; dope trace elements into interface regions; impart specific chemical functionalities to a surface; toughen materials; and create micron- and nanometer-scale interface structures. Several examples are developed which demonstrate the variety of technologically important interface modification that is possible with gas phase ions. These examples have been selected to demonstrate how the choice of the ion and its kinetic energy controls modification and deposition for several different materials. Examples are drawn from experiments, computer simulations, fundamental research, and active technological applications. Finally, a list of research areas is provided for which ion–surface modification promises considerable scientific and technological advances in the new millennium.     

Chemical and catalytic effects of ion implantation

Energetic particles are used for inducing chemical reactions as well as for modifying the properties of materials with regard to their bulk and surface chemical behavior. The effects are partly caused by radiation damage or phase intermixing, partly by the chemical properties of the individual bombarding particles. In this contribution a survey of relevant applications of these techniques is presented:

1) Chemical reactions of implanted and recoil atoms and their use for syntheses, doping and labeling of compounds.

2) The formation of thin films by decomposing chemical compounds with ion beams.

3) Catalytic effects on substrates treated by sputtering or ion implantation. Recent results with nonmetallic substrates are reviewed. Mainly hydrogenation reactions at a solid/gas interface or redox reactions at an electrified solid/liquid interface are mentioned.

The present status and future prospects of these kinds of investigations will be discussed.     

Composition-spread thin films of pentacene and 6,13-pentacenequinone fabricated by using continuous-wave laser molecular beam epitaxy

Synthesis of continuous composition-spread (CCS) thin films is widely recognized in combinatorial material science as a powerful technique for rapidly investigating the properties of new functional materials. However, there are very few reports of CCS organic thin films due to the fact that the thermal evaporation method with Knudsen cells, which is commonly used to fabricate organic thin films in vacuum, does not offer the necessary level of deposition rate control as, for example, does pulsed laser deposition (PLD). We have successfully fabricated organic CCS thin films of pentacene and 6,13-pentacenequinone by continuous-wave laser molecular beam epitaxy (CWL-MBE), which we developed as a new fabrication method for organic thin films. The composition-spread films were characterized systematically by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, and two-probe conductivity measurements. The present work brings the advantages of high-throughput parallel synthesis and systematic characterization to the field of organic electronics, allowing for quick exploration and rapid optimization of organic functional materials and devices.     

Tunable photonic crystals based on ferroelectric and ferromagnetic materials by focused ion beam

By making photonic crystals in ferroelectric and ferromagnetic materials, field-provoked tunability of photonic crystals is broadening the interest in new applications of on-chip photonic devices. We report a nano-precise fabrication of various designs of photonic crystals in these non-conventional materials using the focused ion beam milling technique. Standard methods are developed and parameters for different materials are calibrated. Optical responses such as bandgaps and polarization status changing from planar film waveguide system with these patterns have been examined on ferromagnetic materials.     

Solid-phase reactions between (100) GaAs and thin-film refractory metals (Ti,Zr, V,Nb, Cr,Mo, and W)

Recently, there has been an increased interest in the applications of refractory metals as gate materials for the self aligned gate process in the fabrications of GaAs field effect transistors. In this study, we systematically investigated the thermally induced interface interactions between (100) GaAs substrates and thin films of refractory metals (Ti, Zr, V, Nb, Cr, Mo, and W). Depth profilings of the M/GaAs interfaces were obtained using conventional and heavy ion Rutherford backscattering spectrometry. Phase identifications were achieved by x-ray diffraction.Results on the phase formation sequence, reaction kinetics, the distribution, composition and structure of the reacted phases and the interface reactivity of these contacts will be presented. Correlations between metal properties (electronegativity and metal-metal bond strength) and kinetics of the reactions (activation energy and reactivity of the interfaces) will also be discussed.