We investigated the performance of Hall sensors with different Co-C ratios, deposited directly in nanostructured form, using Co(2)(CO)(8) gas molecules, by focused-electron or ion-beam-induced deposition. Due to the enhanced intergrain 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 magnetic field sensitivity of 1 Omega T(-1). We show that the best magnetic field resolution at room temperature is obtained for Co ratios between 60% and 70% and is better than 1 microT Hz(-1/2). For an active area of the sensor of 200 x 200 nm(2), the room temperature magnetic flux resolution is phi(min) = 2 x 10(-5)phi(0) in the thermal noise frequency range, i.e. above 100 kHz.

Electron-beam-induced deposition (EBID), also referred to as focused electron-beam-induced processing (FEBIP), is a lowvacuum materials processing technique in which a focused electron beam is used to directly write nanometer-sized structures onto a substrate in a constant partial pressure of precursor molecules. 1À4 EBID has a unique and attractive combination of capabilities, including high spatial resolution and the flexibility to deposit self-supporting three-dimensional nanostructures on nonplanar surfaces. EBID offers a number of advantages compared to other vacuum-based nanofabrication strategies. EBID is capable of creating smaller features than ion-beaminduced deposition (IBID), with less amorphization and without ion implantation. 5À7 Although the resolution of EBID is comparable to that of electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL), 8,9 it needs no resist layers or etching step for pattern transfer. The advantages of EBID have also been recently been combined with those of atomic layer deposition (ALD) to create purely metallic but geometrically well-defined nanostructures. 10 Current applications of EBID include repairing masks used in UV lithography, 11À14 creating line gratings on vertical cavity surface emitting lasers, 15 and fabricating tips for scanning probe microscopy. 16,17

Impact factor: Electron‐impact dissociation reactions in two‐adsorbate systems were tuned by applying specific exposure conditions in electron microscopes. Pulsed electron‐impact exposure could drive the dissociation reaction of one of the adsorbates into the molecule‐limited regime while the reaction of the other adsorbate continued in the electron‐limited regime. The pulse period gave control over the composition of the deposit (see scheme).

We show that nanocomposite materials consisting of superparamagnetic nanoparticles embedded in a matrix are very good candidates for a novel generation of Hall nanosensors with high spatial and magnetic resolution, capable of detecting superparamagnetic beads suspended at different heights on top of the sensor. Two detection schemes were used: 1) static-the bead was centered on top of the sensor and detected with a combination of ac and dc orthogonal magnetic fields, and 2) dynamic-using nanomanipulation in an electron microscope for moving the bead precisely at different heights above the sensor and using only one magnetic field (ac). The Hall sensors were directly written by focusedelectron-beam-induced deposition and the active area was refined by focused ion beam milling. A magnetic field resolution of about 300 μT(Hz) −1 /2 and a spatial resolution of 230 nm(Hz) −1 /2 were measured. Both resolutions could be improved by at least an order of magnitude with the suppression of the parasitic inductive signals.

Nanoscale electron-induced reactions being triggered by a finely focused electron beam in modern scanning electron microscopes are commonly used to pattern surfaces of thin films of irradiation sensitive material. Classical polymer and inorganic resist films allow precise masks to be defined for further deposition or etching process steps in the semiconductor industry. [1] A new, promising approach employs new film materials, among which are self-assembled monolayers of biphenyl, passivated gold nanoclusters, Langmuir-Blodgett films, or liquid precursors. The exposure of these films to electrons directly results in membranes, electrical wires, plasmonic structures, or conducting dots with nanoscale dimensions. [2] A very promising approach to electron-impact nanosynthesis is to replace the solid or liquid film and use a physisorbed monolayer that is continuously refreshed by injected volatile molecules. [3] The process can be compared to local chemical vapor deposition; however, the decomposition is due to electron-impact dissociation rather than thermal dissociation, thus keeping the reaction confined to the size of the electron beam and the active electron interaction volume. It has been proven to be a very innovative concept for direct, local, three-dimensional, and minimally invasive nanosynthesis of future photonic, [4] electronic, [5] and mechanical [6] nanodevice materials as well as for site-specific patterning of catalyst for individual carbon nanotube growth [7] and atomic layer deposition. [8] For nanoscale deposition, a focused electron beam is usually scanned over surface-adsorbed metal containing compounds that are volatile at room temperature. Electron-impact dissociation of such adsorbates by both the primary beam electrons (with keV energy) and the emitted secondary electrons (with eV energy) results in metalcontaining deposits and volatile reaction products, the latter being removed by the vacuum system. Advantageously, the same principle allows nanoscale removal of material. For example, physisorbed water on carbon surfaces dissociates under electron impact to produce highly reactive species that react to volatile carbon compounds, thus etching a nanosized hole in the substrate when a stationary focused electron beam is used. [9] Injected molecules used for electron-impact nanosynthesis so far comprise various metal-ligand compounds that contain carbon-, phosphorous-, or halogen-based ligands as well as organic compounds. [3] With the recent development of gas injection systems that allow the admission of two or more gases to the substrate surface, the nanosynthesis of binary metal alloys [10] or metal-(carbon) matrix deposits with outperforming properties [5c,e] can be envisaged. In contrast to classical vapor deposition exploiting co-evaporation, the deposit will be locally confined and the composition will depend not only on the ratios of molecule flow adsorption but also on the electron-impact dissociation efficiency of each individual molecule, giving a further degree of freedom to t...