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ABSTRACT: A sensitive nanosized molybdenum oxide (MoO(x)) photodetector is manufactured at a desired position by electron-beam-induced deposition (EBID). As-deposited MoO(x) had a conductivity approximately 300 S cm(-1). After 2 h annealing at 573 K, the conductivity of nanowires decreased 10 times to approximately 30 S cm(-1) and MoO(x) had photoconductivity. Nanosized MoO(x) wires enhanced the sensitivity of optical devices due to an increased surface area to volume ratio.
Nanotechnology 10/2009; 20(42):425305. · 3.98 Impact Factor
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ABSTRACT: An efficient, Bloch wave-based method is presented for simulation of high-resolution scanning confocal electron microscopy (SCEM) images. The latter are predicted to have coherent nature, i.e. to exhibit atomic contrast reversals depending on the lens defocus settings and sample thickness. The optimal defocus settings are suggested and the 3D imaging capabilities of SCEM are analyzed in detail. In particular, by monitoring average image intensity as a function of the probe focus depth, it should be possible to accurately measure the depth of a heavy-atom layer embedded in a light-element matrix.
Ultramicroscopy 08/2008; 108(9):981-8. · 2.47 Impact Factor
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Microscopy and Microanalysis 07/2008; 14:816 - 817. · 3.01 Impact Factor
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ABSTRACT: Measurements of thickness using electron energy loss spectroscopy (EELS) are revised. Absolute thickness values can be quickly and accurately determined with the Kramers-Kronig sum method. The EELS data analysis is even much easier with the log-ratio method, however, absolute calibration of this method requires knowledge of the mean free path of inelastic electron scattering lambda. The latter has been measured here in a wide range of solids and a scaling law lambda approximately rho(-0.3) versus mass density rho has been revealed. EELS measurements critically depend on the excitation and collection angles. This dependence has been studied experimentally and theoretically and an efficient model has been formulated.
Microscopy Research and Technique 06/2008; 71(8):626-31. · 1.79 Impact Factor
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ABSTRACT: The structure of individual nanodiamond grains produced by the detonation of carbon-based explosives has been studied with a high-vacuum aberration-corrected electron microscope. Many grains show a well-resolved cubic diamond lattice with negligible contamination, thereby demonstrating that the non-diamond shell, universally observed on nanodiamond particles, could be intrinsic to the preparation process rather than to the nanosized diamond itself. The strength of the adhesion between the nanodiamond grains, and the possibility of their patterning with sub-nanometer precision, are also demonstrated.
Nanotechnology 04/2008; 19(15):155705. · 3.98 Impact Factor
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ABSTRACT: Electron beam induced deposition (EBID) is a promising technique for fabricating nanometre-sized structures in a position-controlled manner. In this technique, organometallic precursors are decomposed by focused electron beams. Then, the non-volatile part of the decomposed precursor deposits on the substrate. As electron beams can be focused to a subnanometre scale in modern electron microscopes, the resolution of EBID is now reaching down to subnanometres. However, the deposits generally contain a large amount of amorphous carbon. This carbon contamination may be the most serious drawback and is preventing practical uses of EBID in nanodevice technology. In this study, nanostructures, such as nanowires, were fabricated by EBID using methyl cyclopenta dienyl platinum trimethyl (MeCpPtMe3) and iron pentacarbonyl (Fe(CO)5) precursors in a scanning electron microscope with a custom-made gas introduction system. After the deposition, nanostructures were heated at 400°C in air for 30 min. to remove contaminated carbon. Then, the nanostructures were observed using a transmission electron microscope (TEM). TEM observation revealed that a post-deposition heat-treatment in air resulted in the removal of carbon. The nanostructures made from MeCpPtMe3 and Fe(CO)5 became pure Pt and a mixture of hematite and maghemite iron oxides, respectively.
Journal of Physics Conference Series 03/2008; 100(5):052016.
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ABSTRACT: In this paper, nanowires were fabricated by electron beam induced deposition using tetrakis(trifluorophosphite)-metal precursors. The microstructure and composition of the nanostructure were characterized by transmission electron microscopy (TEM).
Microprocesses and Nanotechnology, 2007 Digest of papers; 12/2007
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ABSTRACT: Formation of metal nano-islands on heat-treated substrates by either conventional deposition or by electron beam–induced chemical vapour deposition (EBI-CVD) was performed at elevated temperatures in an ultrahigh vacuum transmission electron microscope (UHV-TEM). Pd islands on SrTiO3 (001) substrates, Pd silicide islands on Si (111) substrates, and Fe silicide islands on Si (111) substrates showed bimodal island growth; both substrates blocked islands and nano-wires. The morphologies of these islands are suggested to be sensitive to the substrate conditions because of heat treatment before deposition. Selective growth of the nano-wires was successful in the case of EBI-CVD. Copyright © 2006 John Wiley & Sons, Ltd.
Surface and Interface Analysis 11/2006; 38(12‐13):1568 - 1572. · 1.18 Impact Factor
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ABSTRACT: The present paper presents the low-energy characteristic X-ray emission from monocrystalline Al2O3 insulator samples in an electric field during positive, low-energy ion (30 keV Ga+ and 100 keV Xe+) bombardment. The electric field built up by the direct current (d.c.) bias was parallel to the surface of the samples. The results show that the characteristic O Kα and Al Kα X rays increased with increase in applied d.c. bias, and that the X-ray yield from the lighter element was more sensitive to the d.c. bias than that from the heavier element. Copyright © 2006 John Wiley & Sons, Ltd.
Surface and Interface Analysis 11/2006; 38(12‐13):1731 - 1733. · 1.18 Impact Factor
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ABSTRACT: Nanowires were formed on a tungsten tip and on an edge of a metal substrate by electron beam induced deposition (EBID), and were made to come in contact with each other in a specially designed transmission electron microscope (TEM) sample holder to perform the measurement of the resistivity of the nanowires. The resistivity of the contacted nanowires was very high (>0.01 Ωm) immediately after making contact. During the resistivity measurement, potential distribution around the contacted nanowires was observed by electron holography, and it was revealed that electric field concentrated on the contact point. It was due to the insulative character of the contact. The irradiation of an intense electron beam decreased such high contact resistance, and electron holographic observation showed that the electric field distribution became uniform. Copyright © 2006 John Wiley & Sons, Ltd.
Surface and Interface Analysis 11/2006; 38(12‐13):1628 - 1631. · 1.18 Impact Factor
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ABSTRACT: It was found that Fe and Pt can be successfully alloyed in rod-like nanostructures by electron-beam-induced deposition (EBID) using a Fe(CO)5 precursor in an ultrahigh vacuum scanning electron microscope (SEM), followed by a 600 °C vacuum heating of the deposit and a subsequent surface platinum coating and a further 600–700 °C annealing treatment. By using high-resolution transmission electron microscopy (HRTEM), image simulation and energy dispersion X-ray spectra analysis, L12-type intermetallic FePt3 phase occurred in the nanostructure formed by the aforementioned EBID and postdeposition alloying processes.
Surface and Interface Analysis 11/2006; 38(12-13):1527–1529. · 1.18 Impact Factor
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Advanced Engineering Materials 08/2006; 8(8):711 - 714. · 1.18 Impact Factor
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Microscopy and Microanalysis 07/2006; 12:980 - 981. · 3.01 Impact Factor
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ABSTRACT: Electron beam induced deposition (EBID) with a mixture gas of iron carbonyl and ferrocene was carried out to fabricate nanostructures with different iron concentrations in a chamber of a scanning electron microscope. The iron concentration was controlled by changing the ratio of partial pressure of iron carbonyl and ferrocene. Electron holography observation revealed that the remanent magnetic flux density B
r values of the nanostructures were also changed depending on the iron concentration.
Journal of Materials Science 06/2006; 41(14):4532-4536. · 2.02 Impact Factor
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ABSTRACT: Electron beam-induced deposition (EBID) using organometallic precursors is a promising technique for nanometre-sized fabrication, but the deposits have been mostly limited to carbonaceous materials. In this study, vapours of water and iron pentacarbonyl were mixed with precise control and the mixture used as a precursor for EBID. We have succeeded in achieving direct formation of Fe3O4 nanostructures at room temperature. This will contribute to broadening the range of materials that can be produced by EBID.
Nanotechnology 06/2006; 17(15):3637. · 3.98 Impact Factor
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ABSTRACT: A nanometer-sized magnet (nano-magnet) was fabricated on the tip of a tungsten needle by electron-beam-induced deposition
with Fe(CO)5 gas. The needle tip, which can be moved with a stepping motor and piezo-driver, was attached inside a specially designed
TEM specimen holder. This nano-magnet on the piezo-driven tip is capable of making an approach to magnetic nanostructures
formed on a substrate so that the nanometer-scale magnetic interaction could be studied. Electron holography observation of
the magnetic field around the nano-magnet showed that the residual magnetic flux density Br of the nano-magnet was about 0.48T.
Journal of Materials Science 04/2006; 41(9):2627-2630. · 2.02 Impact Factor
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ABSTRACT: Focused electron beam induced chemical vapor deposition was performed in a scanning electron microscope with a field emission gun using a precursor of iron carbonyl. Due to the longer deposition time and higher gas pressure than those of our previous electron beam-induced deposition method, a new type of deposition occurred. A large amount of nanosized crystals were produced around the focused beam irradiation point on a carbon substrate at room temperature. The nanocrystals were systematically characterized using transmission electron microscopy with electron energy loss spectroscopy (EELS), and were identified to be single crystals of α-Fe.
Journal of Materials Science 04/2006; 41(9):2577-2580. · 2.02 Impact Factor
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ABSTRACT: Electron-beam induced chemical vapor deposition (EBI-CVD) of Fe(CO)5 was performed on both Si (111) and (110) substrates at 673–873 K inside an ultrahigh vacuum transmission electron microscope. The formation of iron silicide islands was observed on both substrates. Cubic silicide nano-rods were formed on Si(111) substrates by EBI-CVD with focused electron beams. The formation of β-FeSi2 islands was mainly observed on Si(110) substrates by EBI-CVD when the electron beam was broadly spread. It was shown that the size and the intensity of the electron beam played a significant role in EBI-CVD and affected the CVD process extensively.
Journal of Materials Science 04/2006; 41(9):2667-2671. · 2.02 Impact Factor
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ABSTRACT: Well-aligned, ferromagnetic FePt nanorods have been fabricated by electron beam-induced deposition using an ultrahigh-vacuum scanning electron microscope. A mixture gas of iron pentacarbonyl and cyclopentadienylplatinum (IV) trimethyl was used as a precursor and post-annealing at 600 °C for 2 h was performed to accomplish the crystallization process. Each nanorod was composed of a chain of crystalline Fe-Pt alloy nanoparticles encapsulated within a carbon-containing sheath. The nanoparticles were identified to be face centered tetragonal (fct) FePt phase (L1<sub>0</sub>,P4/mmm) by electron diffraction and high-resolution transmission electron microscopy (HRTEM). The residual magnetic flux density B<sub>r</sub> of the nanorods was evaluated to be about 1.53 T via off-axis electron holography, showing a strong ferromagnetic character.
Applied Physics Letters 12/2005; · 3.84 Impact Factor
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ABSTRACT: Increasing attention has been paid to the usage of focused-electron-beam in the field of nanofabrication. It was verified that electron-beam-induced deposition (EBID) is capable of fabricating nanostructures on the nanometer scale. Among various precursors, tungsten hexacarbonyl [W(CO)<sub>6</sub>] has been widely used to repair microelectronic masks and to fabricate supertips. Their properties (e.g. conductivity, field emission) are closely related to the metallic content in the structure (Hoyle, 1994). However, the as-deposited structures of W(CO)<sub>6</sub> are polycrystalline materials, which consist of nanocrystallines (tungsten, tungsten oxides and tungsten carbides) embedded in an amorphous carbon containing matrix (Han, 2004). In order to increase the tungsten content, heating of as-deposited tungsten wire was carried out and its crystallization on molybdenum substrate was investigated in the present study.
Microprocesses and Nanotechnology Conference, 2005 International; 11/2005
