Institute of Sensor and Actuator Systems

The capability to control matter down to the nanoscale level in combination with the novel magnetic properties of nanomaterials have attracted increasing attention in the last few decades due to their applications in magnetic sensing, hard disc data storage and logic devices. Therefore, many efforts have been devoted to the implementation of both nanofabrication methods as well as characterization of magnetic nanoelements. In this study, Fe-based nanostructures have been synthesized on Si(100) by focused electron beam induced deposition (FEBID) utilizing iron pentacarbonyl as precursor. The so obtained nanostructures exhibit a remarkably high iron content (Fe > 80 at.%), expected to give rise to a ferromagnetic behaviour. For that reason, magnetic force microscopy (MFM) analyses were performed on the obtained FEBID Fe nanostructures. Moreover, object oriented micromagnetic framework (OOMMF) magnetic simulations have been executed to study the influence of the geometry on the magnetic properties of iron single-domain nanowires. FEBID is a mask-less nanofabrication method based on the injection of precursor gas molecules in proximity of the deposition area where their decomposition is locally induced by a focused electron beam.The capability to control matter down to the nanoscale level in combination with the novel magnetic properties of nanomaterials have attracted increasing attention in the last few decades due to their applications in magnetic sensing, hard disc data storage and logic devices. Therefore, many efforts have been devoted to the implementation of both nanofabrication methods as well as characterization of magnetic nanoelements. In this study, Fe-based nanostructures have been synthesized on Si(100) by focused electron beam induced deposition (FEBID) utilizing iron pentacarbonyl as precursor. The so obtained nanostructures exhibit a remarkably high iron content (Fe > 80 at.%), expected to give rise to a ferromagnetic behaviour. For that reason, magnetic force microscopy (MFM) analyses were performed on the obtained FEBID Fe nanostructures. Moreover, object oriented micromagnetic framework (OOMMF) magnetic simulations have been executed to study the influence of the geometry on the magnetic properties of iron single-domain nanowires. FEBID is a mask-less nanofabrication method based on the injection of precursor gas molecules in proximity of the deposition area where their decomposition is locally induced by a focused electron beam.

Focused electron beam induced deposition (FEBID) is a novel direct-writing technique to produce noble metal nanostructures. In this work, FEBID has been employed for the first time to fabricate metal-oxide-semiconductor capacitors (MOSCAPs). Experimental parameters such as precursor temperature, substrate temperature and the (de)focus of the electron beam have been optimized to deposit electrode structures of a relatively large area within a short timeframe. Using FEBID, gold electrodes have been deposited on top of an atomic layer deposited (ALD) dielectric aluminum oxide layer. Chemical composition of the produced structures has been studied using energy dispersive X-ray spectroscopy (EDX). Current–voltage (I–V) measurements have confirmed the conductivity of FEBID gold nanowires (NWs). Measured capacitance–voltage (C–V) characteristics of FEBID-fabricated MOSCAP prototypes resemble the typical C–V characteristics of conventionally fabricated MOSCAPs, thus confirming the functionality of our FEBID devices.Illustration of a MOS capacitor fabricated by FEBID. Focused electron beam induced deposition (FEBID) is a novel direct-writing technique to produce noble metal nanostructures. In this work, FEBID has been employed for the first time to fabricate metal-oxide-semiconductor capacitors (MOSCAPs). Experimental parameters such as precursor temperature, substrate temperature and the (de)focus of the electron beam have been optimized to deposit electrode structures of a relatively large area within a short timeframe. Using FEBID, gold electrodes have been deposited on top of an atomic layer deposited (ALD) dielectric aluminum oxide layer. Chemical composition of the produced structures has been studied using energy dispersive X-ray spectroscopy (EDX). Current–voltage (I–V) measurements have confirmed the conductivity of FEBID gold nanowires (NWs). Measured capacitance–voltage (C–V) characteristics of FEBID-fabricated MOSCAP prototypes resemble the typical C–V characteristics of conventionally fabricated MOSCAPs, thus confirming the functionality of our FEBID devices.Illustration of a MOS capacitor fabricated by FEBID.

This work reports on focused electron beam induced deposition (FEBID) using a custom built gas injection system (GIS) equipped with nitrogen as a gas carrier. We have deposited cobalt from Co2(CO)8, which is usually achieved by a heated GIS. In contrast to a heated GIS, our strategy allows avoiding problems caused by eventual temperature gradients along the GIS. Moreover, the use of the gas carrier enables a high control over process conditions and consequently the properties of the synthesized nanostructures. Chemical composition and growth rate are investigated by energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM), respectively. We demonstrate that the N2 flux is strongly affecting the deposit growth rate without the need of heating the precursor in order to increase its vapour pressure. Particularly, AFM volume estimation of the deposited structures showed that increasing the nitrogen resulted in an enhanced deposition rate. The wide range of achievable precursor fluxes allowed to clearly distinguish between precursor- and electron-limited regime. With the carrier-based GIS an optimized deposition procedure with regards to the desired deposition regime has been enabled

Magnetic materials synthesized on the nanometer-scale level are essential for several applications, such as spintronics and magnetologic. As a successful nanofabrication approach, focused electron beam-induced deposition (FEBID) stands out as a direct-write technique. FEBID uses an electron beam to locally induce a CVD process, avoiding the use of masks and resists. In this work, Fe–based nanostructures are synthesized on Si(100) by FEBID, starting from iron pentacarbonyl. A systematic variation of FEBID parameters is performed, to study their influence on the geometry and composition of the deposit. Based on the results, specific deposition conditions are suggested for magneto-logic applications and fabrication of large structures.

Among various multi-metal combinations, Au-Fe nanoalloys are envisaged as prospective materials for data storage applications. Here we report on the first successful achievement of Au-Fe nanoalloys using focused electron beam-induced deposition (FEBID), exploiting the possibility of directly writing nanostructures at nanometer resolution. Gaseous organometallic precursors are injected simultaneously into the deposition chamber to co-deposit Fe and Au within the same nanostructure. Fabricated nanostructures show a spatially uniform elemental ratio of iron to gold that can be tailored by experimental conditions.

Nanomagnet logic (NML) is a relatively new
computation technology that uses arrays of shape-controlled
nanomagnets to enable digital processing. Currently, conventional resist-based lithographic processes limit the design of NML circuitry to planar nanostructures with homogeneous thicknesses. Here, we demonstrate the focused electron beam induced deposition of Fe-based nanomaterial for magnetic inplane nanowires and out-of-plane nanopillars. Three-dimensional (3D) NML was achieved based on the magnetic coupling between nanowires and nanopillars in a 3D array. Additionally, the same Fe-based nanomaterial was used to produce tilt-corrected high-aspect-ratio probes for the accurate magnetic force microscopy (MFM) analysis of the fabricated 3D NML gate arrays. The interpretation of the MFM measurements was supported by magnetic simulations using the Object Oriented MicroMagnetic Framework. Introducing vertical out-of-plane nanopillars not only increases the packing density of 3D NML but also introduces an extra magnetic degree of freedom, offering a new approach to input/output and processing functionalities in nanomagnetic computing.

Three-dimensional gold (Au) nanostructures offer promise in nanoplasmonics, biomedical applications, electrochemical sensing and as contacts for carbon-based electronics. Direct-write techniques such as focused-electron-beam-induced deposition (FEBID) can provide such precisely patterned nanostructures. Unfortunately, FEBID Au traditionally suffers from a high nonmetallic content and cannot meet the purity requirements for these applications. Here we report exceptionally pure pristine FEBID Au nanostructures comprising submicrometer−large monocrystalline Au sections. On the basis of high-resolution transmission electron microscopy results and Monte Carlo simulations of electron trajectories in the deposited nanostructures, we propose a curing mechanism that elucidates the observed phenomena. The in situ focused-electron-beam-induced curing mechanism was supported by postdeposition ex situ curing and, in combination with oxygen plasma cleaning, is utilized as a straightforward purification method for planar FEBID structures. This work paves the way for the application of FEBID Au nanostructures in a new generation of biosensors and plasmonic nanodevices.