Transmission electron microscopy of scanning tunneling tips

Garnæs, Jørgen; Kragh, Frank; Mørch, Knud Aage; Thölén, A.R.

doi:10.1116/1.576417

Cited by 58 publications

(22 citation statements)

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“…Characterization by atomic force microscopy (AFM) showed that this etching treatment produced a smooth surface with typical roughness of 3 to 10 nm. It is highly likely that a thin oxide film forms on the electrochemically etched surface of tungsten [17]; such surface oxide layers can affect the results of nanoindentation tests [18]. In addition,…”

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confidence: 99%

Effect of hydrogen on the slip resistance of tungsten single crystals

Yao

Wang

Manhard

et al. 2013

Materials Science and Engineering: A

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The intense influx of hydrogen plasma onto the tungsten wall of a nuclear fusion reactor causes severe microstructural damage in the near-surface layer. The evolution of hydrogen-induced damage is often promoted by local plastic flow. Since hydrogen solutes are known to lower the hardness of many metals, the question arises as to the extent to which the tungsten walls are softened by the implantation of hydrogen. In this study, we investigated the change in slip resistance of tungsten single crystals following deuterium implantation. To determine the inherent yield stress of tungsten, we performed nanoindentation on high-purity single crystals. The statistical distribution of pop-in stresses (yield stress upon a single slip) revealed a significant reduction in pop-in load upon hydrogen implantation. In addition, the average stress at pop-in was found to be a function of crystallographic orientation of the samples, with much larger pop-in loads observed on (100) and (110) surface planes than on (111) surfaces.

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confidence: 99%

Effect of hydrogen on the slip resistance of tungsten single crystals

Yao

Wang

Manhard

et al. 2013

Materials Science and Engineering: A

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“…Furthermore, the reaction at the anode involves the formation of bubbles, which is not mentioned in the reaction above. The formation of an oxide layer during electrochemical etching is discussed in several papers [99,112,113], though none of them really concludes on the dependency of its thickness on the applied external parameters like the bias voltage, current density, OH − concentration etc.…”

Section: Tungsten Tipsmentioning

confidence: 99%

Cryogenic AFM-STM for mesoscopic physics

Sueur

2008

Ann. Phys. Fr.

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Electronic spectroscopy based on electron tunneling gives access to the electronic Density of States (DoS) in conductive materials, and thus provides detailed information about their electronic properties. During this thesis work, we have developed a microscope in order to perform spatially resolved (10 nm) tunneling spectroscopy, with an unprecedented energy resolution (10 µeV), on individual nanocircuits. This machine combines an Atomic Force Microscope (AFM mode) together with a Scanning Tunneling Spectroscope (STS mode), and functions at very low temperatures (30mK). In the AFM mode, the sample topography is recorded using a piezoelectric quartz tuning fork, which allows locating and imaging nanocircuits. Tunneling can then be performed on conductive areas of the circuit. With this microscope, we have measured the local DoS in a hybrid Superconductor-Normal metal-Superconductor (S-N-S) structure. In such circuit, the electronic properties of N and S are modified by the superconducting proximity effect. In particular, for short N wires, we have observed a minigap in the DoS of the N wire, independent of position. Moreover, when varying the superconducting phase difference between the S electrodes, we have measured the modification of the minigap, and its disappearance when the phase difference equals π. Our experimental results for the DoS, and its dependences (with phase, position, N length) are quantitatively accounted for by the quasiclassical theory of superconductivity. Some predictions of this theory are observed for the first time. CRYOGENIC AFM-STM FOR MESOSCOPIC PHYSICSH COVER:The front cover shows an AFM image of a small circuit fabricated by electronic lithography and double angle evaporation, comprising a 350 nm long, 30 nm thick silver wire (colorized in orange) and a 60 nm thick aluminium half loop (dark grey). This structure has been imaged using an atomic force sensor, and tunneling spectroscopy was subsequently performed at several positions. Curves on the background are tunneling spectra measured for different values of the superconducting phase difference across the normal wire (at the location of the tip represented on the AFM image).The graph on the backside of the cover is a 3D plot of the predicted local density of states along a 1D S-N-S structure, with a normal wire length L = 1.4 ξ (corresponding to 350 nm), and perfect interfaces. Merci infiniment à Daniel Esteve, mon directeur de thèse, pour avoir appuyé sans réserve ma candidature, et tout ce qui s'en est suivi : Travailler avec un « chef » comme toi est un enrichissement extrême, tant pour ton recul sur la compréhension des phénomènes envisagés, que pour ton esprit pratique qui nous permet de parvenir plus vite (et mieux bien sûr !) au résultat souhaité… Et puis tu n'es pas chef pour rien : ce don d'ubiquité qui te permet de consacrer à tous les projets simultanément la même attention exclusive force sincèrement l'admiration ! J'espère avoir mérité toute la confiance que m'a accordée Philippe Joyez en me laissant la responsabili...

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“…Huge number of works on the fabrication of sharp tips have been performed and several techniques have been developed, such as grinding [2,12], cutting [13][14][15][16], mechanical pulling [17][18][19][20][21][22][23][24][25][26][27], chemical or electrochemical etching , field evaporation or other field-induced methods [72][73][74][75][76], beam deposition [77][78][79][80][81][82][83], ion milling [15,[84][85][86][87][88][89][90][91][92][93][94], and others [95].…”

Section: Introductionmentioning

confidence: 99%

Dynamic electrochemical-etching technique for tungsten tips suitable for multi-tip scanning tunneling microscopes

Hobara

Yoshimoto

Hasegawa

et al. 2007

e-J. Surf. Sci. Nanotech.

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We present a method to prepare tungsten tips for use in multi-tip scanning tunneling microscopes. The motivation behind the development comes from a requirement to make very long and conical-shape tips with controlling the cone angle. The method is based on a combination of a "drop-off" method and dynamic electrochemical etching, in which the tip is continuously and slowly drawn up from the electrolyte during etching. Its reproducibility was confirmed by scanning electron microscopy. Comparison in tip shape between the dynamic and static methods was shown.

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Transmission electron microscopy of scanning tunneling tips

Cited by 58 publications

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Effect of hydrogen on the slip resistance of tungsten single crystals

Effect of hydrogen on the slip resistance of tungsten single crystals

Cryogenic AFM-STM for mesoscopic physics

Dynamic electrochemical-etching technique for tungsten tips suitable for multi-tip scanning tunneling microscopes

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