Post-growth purification of Co nanostructures prepared by focused electron beam induced deposition (original) (raw)
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High-purity cobalt nanostructures grown by focused-electron-beam-induced deposition at low current
Microelectronic Engineering, 2010
Focused-electron-beam-induced deposition (FEBID) allows the creation of three-dimensional nanostructures of different materials using the appropriate precursor material. The fabrication of magnetic nanopatterns by means of this direct-write technique is an interesting alternative to more conventional lithographic methods. In the present work, we explore the use of the FEBID technique to grow Co nanostructures with high-purity (>90% at.) using dicobalt octacarbonyl [Co 2 (CO) 8 ] and with low beam currents (pA range), thus guaranteeing the high lateral resolution of the nanodeposits. It is found that under such low beam currents, the Co content can be greatly enhanced if the substrate temperature is increased at 100°Cbymeansofamicro−hotplate.Theoccurrenceofthermaldecompositionoftheprecursormoleculesincontactwiththemicro−hotplatehasbeenobservedat100°C by means of a micro-hotplate. The occurrence of thermal decomposition of the precursor molecules in contact with the micro-hotplate has been observed at 100°Cbymeansofamicro−hotplate.Theoccurrenceofthermaldecompositionoftheprecursormoleculesincontactwiththemicro−hotplatehasbeenobservedat200°C. These results also demonstrate the important role played by local heating effects in the Co content attained in the deposits.
Review of magnetic nanostructures grown by focused electron beam induced deposition (FEBID)
Journal of Physics D: Applied Physics, 2016
We review the current status of the use of focused electron beam induced deposition (FEBID) for the growth of magnetic nanostructures. This technique relies on the local dissociation of a precursor gas by means of an electron beam. The most promising results have been obtained using the Co 2 (CO) 8 precursor, where the Co content in the grown nanodeposited material can be tailored up to more than 95%. Functional behaviour of these Co nanodeposits has been observed in applications such as arrays of magnetic dots for information storage and catalytic growth, magnetic tips for scanning probe microscopes, nano-Hall sensors for bead detection, nano-actuated magnetomechanical systems and
Nanoscale chemical and structural study of Co-based FEBID structures by STEM-EELS and HRTEM
Nanoscale Research Letters, 2011
Nanolithography techniques in a scanning electron microscope/focused ion beam are very attractive tools for a number of synthetic processes, including the fabrication of ferromagnetic nano-objects, with potential applications in magnetic storage or magnetic sensing. One of the most versatile techniques is the focused electron beam induced deposition, an efficient method for the production of magnetic structures highly resolved at the nanometric scale. In this work, this method has been applied to the controlled growth of magnetic nanostructures using Co 2 (CO) 8 . The chemical and structural properties of these deposits have been studied by electron energy loss spectroscopy and high-resolution transmission electron microscopy at the nanometric scale. The obtained results allow us to correlate the chemical and structural properties with the functionality of these magnetic nanostructures.
Engineered magnetization and exchange stiffness in direct-write Co–Fe nanoelements
Applied Physics Letters
Media with engineered magnetization are essential building blocks in magnonics, spintronics, and superconductivity. However, the established thin film and lithographic techniques insufficiently suit the realization of planar components with on-demand-tailored magnetization in the lateral dimension. Here, we demonstrate the engineering of the magnetic properties of CoFe-based nanodisks fabricated by the mask-less technique of focused electron beam-induced deposition (FEBID). The material composition in the nanodisks is tuned in situ via the e-beam waiting time in the FEBID process and their post-growth irradiation with Ga ions. The saturation magnetization M s and exchange stiffness A of the disks are deduced from perpendicular spin-wave resonance measurements. The achieved M s variation in the broad range from 720 emu/cm 3 to 1430 emu/cm 3 continuously bridges the gap between the M s values of widely used magnonic materials such as Permalloy and CoFeB. The presented approach paves the way toward nanoscale 2D and 3D systems with controllable space-varied magnetic properties.
Beilstein Journal of Nanotechnology, 2021
Focused electron beam-induced processing is a versatile method for the fabrication of metallic nanostructures with arbitrary shape, in particular, on top of two-dimensional (2D) organic materials, such as self-assembled monolayers (SAMs). Two methods, namely electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) are studied with the precursors Fe(CO)5 and Co(CO)3NO on SAMs of 1,1′,4′,1′′-terphenyl-4-thiol (TPT). For Co(CO)3NO only EBID leads to deposits consisting of cobalt oxide. In the case of Fe(CO)5 EBID and EBISA yield deposits consisting of iron nanocrystals with high purity. Remarkably, the EBISA process exhibits a strong time dependence, which is analyzed in detail for different electron doses. This time dependence is a new phenomenon, which, to the best of our knowledge, was not reported before. The electron-induced cross-linking of the SAM caused by the cleavage of C–H bonds and the subsequent formation of new C–C bonds between neighbo...
High spatial resolution Hall nano-sensors by tuned direct-write Co/C-FEBID
2011
Gas assisted focused electron beam induced deposition is a direct write technique that allows for the deposition of nanoscale structures inside standard scanning electron microscopes. Here we show that the composition of the nano-deposits can depend on their size, which can be used as an additional parameter, besides the control of the beam dwell time, in order to tune the metal/matrix ratio and to obtain new nanoscale materials with tailored properties. By optimizing the Cobalt/Carbon ratio and the size of the active area, it was possible to obtain superparamagnetic Hall sensors with outstanding magnetic spatial resolution. These sensors have been successfully used for detecting single paramagnetic micro-beads commonly used as labels in biological and medical research.
Capping layer effects in the structure and composition of Co nanoparticle ultrathin films
Applied Physics Letters, 2005
In this work, we present the correlation of the magnetic and structural properties of Co nanoparticles deposited by sputtering on Si 3 N 4 substrates at different temperatures, and covered with different capping layers, two insulators, AlN and MgO, and a metal, Pt. High-resolution transmission electron microscopy shows the formation of CoPt 3 and Co 2 N, for the Pt and AlN capping layers, respectively, giving to a significant change of the magnetic behavior. When using a cap of MgO, energy-filtered transmission electron microscopy shows an oxidized shell covering the Co nanoparticles with thickness decreasing as the deposition temperature increases, explaining the changes in the magnetic response induced by the MgO capping layer.
Ultrasmall Functional Ferromagnetic Nanostructures Grown by Focused Electron-Beam-Induced Deposition
ACS Nano, 2011
We have successfully grown ultrasmall cobalt nanostructures (lateral size below 30 nm) by optimization of the growth conditions using focused electron-beam-induced deposition techniques. This direct-write nanolithography technique is thus shown to produce unprecedented resolution in the growth of magnetic nanostructures. The challenging magnetic characterization of such small structures is here carried out by means of electron holography techniques. Apart from growing ultranarrow nanowires, very small Hall sensors have been created and their large response has been unveiled.