166 research outputs found
Nano-Hall sensors with granular Co-C
We analyzed the performance of Hall sensors with different Co-C ratios,
deposited directly in nano-structured form, using gas molecules,
by focused electron or ion beam induced deposition. Due to the enhanced
inter-grain scattering in these granular wires, the Extraordinary Hall Effect
can be increased by two orders of magnitude with respect to pure Co, up to a
current sensitivity of . We show that the best magnetic field
resolution at room temperature is obtained for Co ratios between 60% and 70%
and is better than . For an active area of the sensor of , the room temperature magnetic flux resolution is , in the thermal noise frequency range, i.e. above 100
kHz.Comment: 5 pages, 4 figure
Coordination and organometallic precursors of group 10 and 11 Focused electron beam induced deposition of metals and insight gained from chemical vapour deposition, atomic layer deposition, and fundamental surface and gas phase studies
Nanostructured materials made from group 10 Ni, Pd, Pt and group 11 Cu, Ag, Au elements have outstanding technological relevance in microelectronics, nano optics, catalysis, and energy conversion. Processes that allow for the easy and reliable fabrication of such nanostructures are heavily sought after. Focused electron beam induced deposition FEBID is the only direct write technique that can fabricate nanostructures with arbitrary shape and dimensions down to the sub 10 nm regime. However, the complex chemistry of FEBID involving electron induced dissociation processes of metalorganic precursors molecules, surface kinetics, and thermal effects is poorly understood and far from being optimized. Here, we review in a comparative manner the performance and the underlying chemical reactions of surface deposition processes, namely, chemical vapour deposition CVD , atomic layer deposition ALD , and FEBID itself. The knowledge gained in CVD and ALD as related surface deposition techniques will help us to understand the spatially selective chemistry occurring in FEBID. Fundamental surface and gas phase studies provide insight to electron induced chemistry and desorption of precursor fragments. Specific emphasis is put on the type of the ligands and their different behaviour under thermal, surface related, and electron induced processes. The comprehensive overview of the current state of FEBID for group 10 and 11 metals includes reactive environments and purification approaches as these may provide valuable information on the design of novel precursors. The evaluation of the precursor and process performance is extended to include W, Co, Fe, Ru, Rh, and Ir to represent a general guide towards future developments in FEBID. These may not only rely on the design of novel compounds but also on optimized deposition strategies inspired by ALD and CV
Gas assisted silver deposition with a focused electron beam
Focused electron beam induced deposition FEBID is a flexible direct write method to obtain defined structures with a high lateral resolution. In order to use this technique in application fields like plasmonics, suitable precursors which allow the deposition of desired materials have to be identified. Well known for its plasmonic properties, silver represents an interesting candidate for FEBID. For this purpose the carboxylate complex silver I pentafluoropropionate AgO2CC2F5 was used for the first time in FEBID and resulted in deposits with high silver contents up to 76 at. . As verified by TEM investigations, the deposited material is composed of pure silver crystallites in a carbon matrix. It showed good electrical properties and a strong Raman signal enhancement. Interestingly, silver crystal growth presents a strong dependency on electron dose and precursor refreshment
Hydrogen sorption in the LiH-LiF-MgB2 system
A composite material in the LiH-LiF-MgB2 system has been synthesized by high-energy ball milling. Some peaks in addition to that of the binary 2LiH-MgB2 and 2LiF-MgB2 systems are observed for the composite material by high-pressure differential scanning calorimetry (HP-DSC), indicating the formation of intermediate phases. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) performed at 60 bar of H-2 and 390 degrees C shows a superposition of both reaction pathways that are typical for 2LiH-MgB2 and 2LiF-MgB2. After hydrogen absorption of the LiH-LiF-MgB2 composite the vibrational modes of LiBH4 were observed by attenuated total reflection infrared (ATR-IR) spectroscopy. The F-19 MAS NMR spectrum of the LiF-LiBH4 sample after heat treatment in hydrogen is strongly dominated by the centerband and spinning sidebands from LiF; in addition, a low-intensity resonance, very similar to that of [BF4](-) ion, is identified
Towards the third dimension in direct electron beam writing of silver
Carboxylates constitute an extremely promising class of precursor compounds for the electron beam induced deposition of silver. In this work both silver 2,2 dimethylbutyrate and silver pentafluoropropionate were investigated with respect to their dwell time dependent deposition behavior and growth characteristics. While silver 2,2 dimethylbutyrate showed a strong depletion in the center of the impinging electron beam profile hindering any vertical growth, silver pentafluoropropionate indicated a pronounced dependency of the deposit height on the dwell time. Truly three dimensional silver structures could be realized with silver pentafluoropropionate. The pillars displayed a polycrystalline habit with silver contents of more than 50 at. and strong Raman enhancement constituting a promising route towards direct electron beam writing of three dimensional plasmonic device parts from the gas phase
Dose and energy dependence of mechanical properties of focused electron beam induced pillar deposits from Cu(C5HF6O2)2
Bending and vibration tests performed inside the scanning electron microscope
were used to mechanically characterize high-aspect pillars grown by focused
electron-beam (FEB) induced deposition from the precursor Cu(C5HF6O2)2.
Supported by finite element (FE) analysis the Young's modulus was determined
from load-deflection measurements using cantilever-based force sensing and the
material density from additional resonance vibration analysis. The pillar
material consisted of a carbonaceous (C, O, F, H containing) matrix which
embeds 5...10 at. % Cu deposited at 5 keV and 20 keV primary electron energy
and 100 pA beam current, depending on primary electron energy. Young's moduli
of the FEB deposits increased from 17+/-6 GPa to 25+/-8 GPa with increasing
electron dose. The density of the carbonaceous matrix shows a dependence on the
primary electron energy: 1.2+/-0.3 g cm-3 (5 keV) and 2.2+/-0.5 g cm-3 (20
keV). At a given primary energy a correlation with the irradiation dose is
found. Quality factors determined from the phase relation at resonance of the
fundamental pillar vibration mode were in the range of 150 to 600 and
correlated to the deposited irradiation energy.Comment: 17 pages, 9 figures, 2 table
Composition Control of Electron Beam Induced Nanodeposits by Surface Pretreatment and Beam Focusing
Electron Beam-Induced Writing of Nanoscale Iron Wires on a Functional Metal Oxide
Electron beam-induced surface activation (EBISA) has been used to grow wires of iron on rutile TiO2(110)-(1 × 1) in ultrahigh vacuum. The wires have a width down to ∼20 nm and hence have potential utility as interconnects on this dielectric substrate. Wire formation was achieved using an electron beam from a scanning electron microscope to activate the surface, which was subsequently exposed to Fe(CO)5. On the basis of scanning tunneling microscopy and Auger electron spectroscopy measurements, the activation mechanism involves electron beam-induced surface reduction and restructuring
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