The future of focused electron beam-induced processing

A perspective is sketched for the field of focused electron beam-induced processing (FEBIP). The FEBIP lithography technique is compared to the very successful resist-based electron beam lithography (EBL) technique. The advantages of FEBIP over EBL are identified, the main advantage being its high spatial resolution. This will enable FEBIP to become an important lithography technique for the fabrication of devices with critical dimension in the range between 1 and 20 nm and serve as a complementary technique to EBL. It will be discussed what needs to be done to achieve this and what the potential applications are.     

Pseudospark produced pulsed electron beam for material processing

An intense pulsed electron beam produced by a pseudospark discharge is used for material processing. The electron beam propagates in a self-focused manner in the background gas. Hardly 12 ns after the beginning of the discharge the fraction of space charge neutralization is about 96%. To sustain the neutralization effect high energy electrons (E <500 keV) are accelerated in radial direction at the beam head, due to strong electric field gradients. At current maximum the beam pinches due to its own magnetic field. At peak current of 400 A and charging voltage up to 16 kV power density reaches 10⁹ W/cm ² on the target surface. Some results of copper thin films are presented. Due to the high expansion velocity of 10⁴ m/s of the ablated target material a copper-matrix has been masked     

In-situ monitoring of optical near-field material processing by electron microscopes

A GaN-to-InGaN interface modification by predeposition of an ultrathin In-rich InGaN incomplete layer followed by a thin triangular InGaN well layer was employed to overcome the negative effects of polarization field on light emission efficiency of InGaN/GaN quantum wells as well as to improve the crystalline quality by avoidance of a significant strain generation and enhanced surfactant effect. Further, the interface modification induced energy band structure engineering reduces the spatial separation of electrons and holes, and thus increases the carrier recombination rate. The improvement in crystalline quality, localized potential fluctuation, and energy band engineering contribute to the significant increase of green emission of the InGaN/GaN quantum wells.     

Spatial chemistry evolution during focused electron beam-induced deposition: origins and workarounds

The successful application of functional nanostructures, fabricated via focused electron-beam-induced deposition (FEBID), is known to depend crucially on its chemistry as FEBID tends to strong incorporation of carbon. Hence, it is essential to understand the underlying mechanisms which finally determine the elemental composition after fabrication. In this study we focus on these processes from a fundamental point of view by means of (1) varying electron emission on the deposit surface; and (2) changing replenishment mechanism, both driven by the growing deposit itself. First, we revisit previous results concerning chemical variations in nanopillars (with a quasi-1D footprint) depending on the process parameters. In a second step we expand the investigations to deposits with a 3D footprint which are more relevant in the context of applications. Then, we demonstrate how technical setups and directional gas fluxes influence final chemistries. Finally, we put the findings in a bigger context with respect to functionalities which demonstrates the crucial importance of carefully set up fabrication processes to achieve controllable, predictable and reproducible chemistries for FEBID deposits as a key element for industrially oriented applications.     

Lateral resolution in focused electron beam-induced deposition: scaling laws for pulsed and static exposure

In this work, we review the single-adsorbate time-dependent continuum model for focused electron beam-induced deposition (FEBID). The differential equation for the adsorption rate will be expressed by dimensionless parameters describing the contributions of adsorption, desorption, dissociation, and the surface diffusion of the precursor adsorbates. The contributions are individually presented in order to elucidate their influence during variations in the electron beam exposure time. The findings are condensed into three new scaling laws for pulsed exposure FEBID (or FEB-induced etching) relating the lateral resolution of deposits or etch pits to surface diffusion and electron beam exposure dwell time for a given adsorbate depletion state.     

Nanoscale electron beam-induced deposition and purification of ruthenium for extreme ultraviolet lithography mask repair

One critical area for the adoption of extreme ultraviolet (EUV) lithography is the development of appropriate mask repair strategies. To this end, we have explored focused electron beam-induced deposition of the ruthenium capping or protective layer. Electron beam-induced deposition (EBID) was used to deposit a ruthenium capping/protective film using the liquid bis(ethylcyclopentyldienyl)ruthenium(II) precursor. The carbon to ruthenium atomic ratio in the as-deposited material was estimated to be ~9/1. Subsequent to deposition, we demonstrate an electron stimulated purification process to remove carbon by-products from the deposit. Results indicate that high-fidelity nanoscale ruthenium repairs can be realized.     

Advances in imaging and electron physics

Collected Scientific Papers of Meghnad Saha. Edited by Santimay Cratterjee. (S. N. Guha Ray at Sree Saraswaty Press Ltd., 1970.) [Pp. xiii + 414.] £6.00. Scope: Survey; library; library (reference). Level: Specialist/postgraduate.

Collected Scientific Papers of Meghnad Saha. Edited by Santimay Cratterjee. (S. N. Guha Ray at Sree Saraswaty Press Ltd., 1970.) [Pp. xiii + 414.] £6.00. Scope: Survey; library; library (reference). Level: Specialist/postgraduate.

Cosmology. By Jean Charon. (Weidenfeld &; Nicolson World University Library, 1970.) [Pp.256.] Hardback £1.75; paperback £0.70. Scope: Survey; library. Level: General reader; undergraduate; school.

Activation Analysis. By M. Rakovi?. (Butterworth Group, 1970.) [Pp. 339.] £6.00. Scope: Textbook; library. Level: Specialist/postgraduate.

Tables for Group Theory. By P. W. Atkins, M. S. Child and C. S. G. Philips. (Oxford University Press, 1970.) [Pp. ii + 32.] 25p. Scope: Library (reference). Level: Specialist/postgraduate; undergraduate.

Physical Applications of Vectors and Tensors. By Horst Teichmann. (George C. Herrap &; Co., Ltd., 1970.) [Pp. x + 235.] £3.25 and £2.60. Scope: Treatise/Textbook. Level: Undergraduate.

Jacobian Elliptic Function Tables. By L. M. Milne-Thomson. (Macmillan &; Co., Ltd., 1970.) [Pp. xi + 123.] $1.65. Scope: Library (reference). Level: For specialists only.

Atomic Spectra. By H. G. Kuhn. (Longmans, 1970.) [Pp. i + 472.] £5.25. Scope: Treatise. Level: Spccialist/postgraduate.

Magnetic Resonance. Edited by C. K. Coogan, Norman S. Ham, S. N. Stuart, J. R. Pilbrow and G. V. H. Wilson. (Plenum Publishing Corporation, 1970.) [Pp. xiii + 386.] $16.00. Scope: Conference proceedings. Level: For specialists only.

An Introduction to Liquid Helium. By John Wilks. (Oxford: Clarendon Press, 1970). [Pp. i + 165.] £1.40. Scope: Survey. Level: Postgraduate.

Introduction to the General Theory of Particle Transfer. By V. Kourganoff. (Gordon and Breach Science Publishers Ltd., 1970.) [Pp. xiii + 216.] £7.00. Scope: Treatise/textbook. Level: Specialist/postgraduate.

Hot Electron Microwave Generators. By John E. Carroll. (Edward Arnold Publishers Ltd., 1970.) [Pp. xiii + 306.] £6.00. Scope: Treatise/textbook Level: Specialist/postgraduate.

Modern Diffraction and Imaging Techniques in Material Science. Edited by S. Amelinckx, R. Gevers, G. Remaut and J. Van Landuyt. (North-Holland, 1970.) [Pp. viii + 745.] £12.60. Scope: Textbook. Level: For specialists only; specialist/postgraduate.

An Introduction to Electronics. By Dennis F. Shaw. (Longmans, 1970.) [Pp. viii + 397.] £3.00. Scope: Treatise/textbook; library. Level: Undergraduate.

Introduction to Semiconductor Devices. By M. J. Morant. (George G. Harrap &; Co. Ltd., 1970.) [Pp. 143.] 90p. Scope: Textbook. Level: Undergraduate.

Thin Film Physics. By O. S. Heavens. (Methuen &; Co. Ltd., 1970.) [Pp. vii + 152.] £2.00. Scope: Survey; library. Level: General reader; specialist/postgraduate.

Optics, Painting and Photography. By M. H. Pirenne. (Cambridge University Press, 1970.) [Pp. xv + 199.] £4.00. Scope: Treatise; library. Level: General reader.

Nuclear Reactions. By D. F. Jackson. (Methuen &; Co., Ltd., 1970.) [Pp. x + 260.] £3.25. Scope: Textbook. Level: Post-graduate.

Particles and their Interactions. By J. G. Powles. (Addison-Wesley Publishing Co., Inc., 1970.) [Pp. xii + 260.] £2.35. Scope: Textbook. Level: Undergraduate/General reader.     

Instrumental requirements for the detection of electron beam-induced object excitations at the single atom level in high-resolution transmission electron microscopy

This contribution touches on essential requirements for instrument stability and resolution that allows operating advanced electron microscopes at the edge to technological capabilities. They enable the detection of single atoms and their dynamic behavior on a length scale of picometers in real time. It is understood that the observed atom dynamic is intimately linked to the relaxation and thermalization of electron beam-induced sample excitation. Resulting contrast fluctuations are beam current dependent and largely contribute to a contrast mismatch between experiments and theory if not considered. If explored, they open the possibility to study functional behavior of nanocrystals and single molecules at the atomic level in real time.     

Advances in positron and electron scattering*

The topical issue on Advances in Positron and Electron Scattering” combines contributionsfrom POSMOL 2015 together with others devoted to celebrate the unprecedented scientificcareers of our loyal colleagues and trusted friends Steve Buckman (Australian NationalUniversity, Australia) and Michael Allan (University of Fribourg, Switzerland) on theoccasion of their retirements. POSMOL 2015, the XVIII International Workshop on Low-EnergyPositron and Positronium Physics and the XIX International Symposium on Electron-MoleculeCollisions and Swarms, was held at Universidade NOVA de Lisboa, Lisboa, Portugal, from17–20 July 2015. The international workshop and symposium allowed to achieve a veryprivileged forum of sharing and developing our scientific expertise on current aspects ofpositron, positronium and antiproton interactions with electrons, atoms, molecules andsolid surfaces, and related topics, as well as electron interactions with molecules inboth gaseous and condensed phases. Particular topics include studies of electroninteractions with biomolecules, electron induced surface chemistry and the study of plasmaprocesses. Recent developments in the study of swarms are also fully addressed.     

NiMnGa nanostructures produced by electron beam lithography and Ar-ion etching

The technologies of electron beam lithography, dry etching and systems integration are investigated to fabricate a series of Ni-Mn-Ga double-beam structures designed with decreasing critical dimensions of 10 μm, 1 μm and 400 nm. Ni-Mn-Ga thin films of 1 μm thickness are deposited by magnetron sputtering and heat-treated in free-standing condition after selective removal of the substrate. Differential scanning calorimetry and electrical resistance measurements on the films show the characteristic features of martensitic transformation above room temperature. First optical beam deflection experiments demonstrate the magnetic and thermal actuation performance of the double-beam structures.     

Modification in etching characteristics and surface topography of some electron irradiated polymers

Track formation in polymers is a complex phenomenon in which not only primary but also secondary processes, such as formation of radicals and chemical processes, are involved. In the present work, the influence of 2 MeV electrons on the etching properties and the surface topography of polyethylene terephthalate (PET) and polyimide (PI) are studied. The increase in the bulk etch-rate and a decrease in the activation energy of etching were observed for both the polymers. The surface roughness of both polymers was reduced due to electron irradiation.     

Ultrafast electron microscopy in material science

Recent advances in the ultrafast transmission electron microscope(UTEM), with combined spatial and temporal resolutions, have made it possible to directly visualize the atomic, electronic, and magnetic structural dynamics of materials.In this review, we highlight the recent progress of UTEM techniques and their applications to a variety of material systems.It is emphasized that numerous significant ultrafast dynamic issues in material science can be solved by the integration of the pump–probe approach with the well-developed conventional transmission electron microscopy(TEM) techniques. For instance, UTEM diffraction experiments can be performed to investigate photoinduced atomic-scale dynamics, including the chemical reactions, non-equilibrium phase transition/melting, and lattice phonon coupling. UTEM imaging methods are invaluable for studying, in real space, the elementary processes of structural and morphological changes, as well as magnetic-domain evolution in the Lorentz TEM mode, at a high magnification. UTEM electron energy-loss spectroscopic techniques allow the examination of the ultrafast valence states and electronic structure dynamics, while photoinduced near-field electron microscopy extends the capability of the UTEM to the regime of electromagnetic-field imaging with a high real space resolution.     

Photoacoustic and related photothermal techniques

We review the theory and applications of the photoacoustic and related methods belonging to the general area of photothermal measurement techniques. This essay is intended for researchers especially unfamiliar with the basic ideas and potentialities of this rapidly developing field. The applications of photothermal techniques include spectroscopic applications, such as infrared and microwave spectroscopies, monitoring of non-radiative deexcitation processes, biological applications, and measurements of thermal properties.     

Advances in nanomagnetism via X-ray techniques

This report examines the current status and the future directions of the field of nanomagnetism and assesses the ability of hard X-ray synchrotron facilities to provide new capabilities for making advances in this field. The report first identifies major research challenges that lie ahead in three broadly defined subfields of nanomagnetism: confined systems, clusters and complex oxides. It then examines the relevant experimental capabilities that are currently available at hard X-ray synchrotron light sources, using the Advanced Photon Source (APS) at Argonne as an example. Finally, recommendations are made for future development in X-ray facilities that will enhance the study of nanomagnetism, including new experimental directions, modifications that would enable in situ sample preparation, and measurements at high magnetic fields and/or low temperatures. In particular, in situ sample preparation is of high priority in many experiments, especially those in the area of surface magnetism.     

太赫兹波三维成像技术研究进展

太赫兹波具有良好的光谱特性、非电离性和对许多非极性材料具有穿透性,在无损探伤、安检、生物医学诊断、艺术品鉴别等领域表现出许多独特的优点。特别是,太赫兹波三维成像技术能够实现样品内部信息探测,逐渐成为当前的研究热点,并展现出广阔的发展前景。本文重点介绍了太赫兹波三维成像的几种常用技术,包括其基本原理和对应的研究进展,并分析了存在的问题和发展趋势。     

电子显微学进展及其在材料科学中的应用

文章简要介绍了高分辨电子显微学方法和电子能量损失谱的进展.文中特别指出,随着电子显微技术的发展,原子分辨电子显微图像对结构问题的深入研究有重要作用.装备有能量单色器的新一代电子显微镜,可以直接给出高能量分辨率的电子能量损失谱(优于 0.1eV).这些先进技术方法的应用,推动了晶体结构学、材料科学、物理学、纳米科学及生命科学的发展,也为解决很多重要结构问题奠定了基础.文章重点讨论了几个典型功能材料体系的结构问题：利用大角度会聚束电子衍射技术,分析了应变硅器件中的应变分布;利用原位电子显微技术,研究了新型电子铁电体LuFe2O4电荷序和物理性能的关系;深入探讨了强关联体系中电子关联效应对电子能量损失谱和电子结构的影响.     

单帧图像的超分辨率技术进展

单帧图像超分辨率重建是就是由一幅降质的含噪的低分辨率图像来估计一幅高分辨率图像。列举了当前研究的几种主要算法,从峰值信噪比、框架相似性和边缘稳健性的标准来加以比较。最后的结果显示RS算法性能最优,这也符合主观评价标准。     

Refractive index and material dispersion in relativistic electron optics

The refractive index and material dispersion associated with relativistic motion of electrons are calculated. Moreover, the wavelength dependence of refractive index is compared with the Sellmeier model for the index of refraction of lightwaves.