Improved FEBID materials portfolio; pure metals, pure oxides, possibly nitrides

Based on the improved deposit purity and composition control achieved according to the immediate objectives of CELINA but also by new processes that were not anticipated initially, the available portfolio of FEBID materials has substantially increased. This includes (i) pure metals, (ii) bimetallic phases with well-defined composition, and (iii) more complex layered or even patterned nanoscale materials. Furthermore, several other types of materials are emerging but have not yet been published.

Pure Pt and Au have been achieved through a robust process using water as purification reagent that is even applicable to complex freestanding 3D nanostructures:

• Barbara Geier, Christian Gspan, Robert Winkler, Roland Schmied, Jason D. Fowlkes, Harald Fitzek, Sebastian Rauch, Johannes Rattenberger, Philip D. Rack, Harald Plank:
  Rapid and highly compact purification for focused electron beam induced deposits: a low temperature approach using electron stimulated H₂O reactions,
  J. Phys. Chem. C 118, 25 (2014) 14009–14016.

• Mostafa M. Shawrav, Philipp Taus, Heinz D. Wanzenboeck, M. Schinnerl, M. Stöger-Pollach, S. Schwarz, A. Steiger-Thirsfeld, Emmerich Bertagnolli:
  Highly conductive and pure gold nanostructures grown by electron beam induced deposition,
  Sci. Rep. 6, 34003; doi: 10.1038/srep34003 (2016).

• Robert Winkler, Franz-Philipp Schmidt, Ulrich Haselmann, Jason D. Fowlkes, Brett B. Lewis,
  Gerald Kothleitner, Philip D. Rack, Harald Plank:
  Direct-Write 3D Nanoprinting of Plasmonic Structures,
  ACS Appl. Mater. Interfaces 9 (2017) 8233−8240.

Novel Ag precursors enable the fabrication of Ag nanostructures with up to 75% metal content:

• Katja Höflich, Jakub Jurczyk, Yucheng Zhang, Marcos V. Puydinger dos Santos, Maximilian Götz, Carlos Guerra-Nuñez, James P. Best, Czeslaw Kapusta, Ivo Utke:
  Direct Electron Beam Writing of Silver-Based Nanostructures
  ACS Appl. Mater. Interfaces, 9 (2017) 24071–24077.

• Luisa Berger, Katarzyna Madajska, Iwona B. Szymanska, Katja Höflich, Mikhail N. Polyakov, Jakub Jurczyk, Carlos Guerra-Nuñez, Ivo Utke,
  Gas-assisted silver deposition with a focused electron beam
  Beilstein J. Nanotechnol. 9 (2018) 224–232.

Pure Cu phases have been obtained by post-deposition annealing leading to segregation of Cu from the as-deposited carbon matrix:

• Aleksandra Szkudlarek, Alfredo Rodrigues Vaz, Yucheng Zhang, Andrzej Rudkowski, Czesław Kapusta, Rolf Erni, Stanislav Moshkalev, Ivo Utke:
  Formation of pure Cu nanocrystals upon post-growth annealing of Cu–C material obtained from focused electron beam induced deposition: comparison of different methods,
  Beilstein J. Nanotechnol. 6 (2015) 1508–1517.

3D cobalt nanowires can be grown with simultaneous high metallic content (up to 85%) and small diameter following optimization of the growth parameters:

• Javier Pablo-Navarro, Dédalo Sanz-Hernández, César Magén, Amalio Fernández-Pacheco, José María de Teresa:
  Tuning shape, composition and magnetization of 3D cobalt nanowires grown by focused electron beam induced deposition,
  J. Phys. D: Appl. Phys. 50 (2017) 18LT01 (9pp).

Optimal composition control has been achieved using the bimetallic precursor HFeCo₃(CO)₁₂ but also silahexanes that yield a deposit with composition corresponding to the Si:C ratio of the precursor:

• F. Porrati, M. Pohlit, J. Müller, S. Barth, F. Biegger, C. Gspan, H. Plank, M. Huth:
  Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor,
  Nanotechnology 26 (2015) 475701.

• Ragesh Kumar T P, Sangeetha Hari, Krishna K Damodaran, Oddur Ingólfsson, Cornelis W. Hagen:
  Electron beam induced deposition of silacyclohexane and dichlorosilacyclohexane: the role of dissociative ionization and dissociative electron attachment in the deposition process,
  Beilstein J. Nanotechnol. 8 (2017) 2376–2388.8

In another approach, deposits with defined composition such as FeSi and Fe₃Si or a CoPt L₁₀ phase well-controlled composition and magnetic properties have been fabricated by electron irradiation and annealing of multilayer structures to induce atomic species intermixing:

• F. Porrati, R. Sachser, G. C. Gazzadi, S. Frabboni, and M. Huth:
  Fabrication of FeSi and Fe₃Si compounds by electron beam induced mixing of [Fe/Si]₂ and [Fe₃/Si]₂ multilayers grown by focused electron beam induced deposition,
  J. Appl. Phys. 119 (2016) 234306.

• Oleksandr V. Dobrovolskiy, Maksym Kompaniiets, Roland Sachser, Fabrizio Porrati, Christian Gspan, Harald Plank, Michael Huth:
  Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures,
  Beilstein J. Nanotechnol. 6 (2015) 1082–1090.

More recent FEBID materials developments have been summarized in a recent review:

• M. Huth, F. Porrati, O.V. Dobrovolskiy:
  Focused electron beam induced deposition meets material science,
  Microelectronic Engineering 185-186 (2017) 9–28.

A topical review article summarizes the state of magnetic nanodeposits grown by FEBID:

• J.M. De Teresa, A. Fernández-Pacheco, R. Córdoba, L. Serrano-Ramón, S. Sangiao, M.R. Ibarra:
  Review of magnetic nanostructures grown by focused electron beam induced deposition,
  J. Phys. D: Appl. Phys. 49 (2016) 243003.

Several other interesting material developments have been proposed or are ongoing. This includes an approach that uses conversion instead of deposition. This so-called FEBIC process has been used to create nanostructures consisting of a biomaterial:

• Thomas Ganner, Jürgen Sattelkow, Bernhard Rumpf, Manuel Eibinger, David Reishofer, Robert Winkler, Bernd Nidetzky, Stefan Spirk, Harald Plank:
  Direct-Write Fabrication of Cellulose Nano-Structures via Focused Electron Beam Induced Nanosynthesis,
  Scientific Reports 6 (2016) 32451.

A theoretical study suggests that Co₁₈O₁₇ nanoparticles have a potential to be used as precursor for FEBID:

• Veranika Skachkova, Jelena Tamuliene, Viktor Stempitsky:
  Usage of cobalt oxide particles as precursor for FEBID: Ab initio study,
  J Nanopart Res 18 (2016) 264-273.

Other ongoing research concerns, for instance, the fabrication of Cu-Au alloys for sensing applications from a mixture of precursors, and studies aiming at the fabrication of a nitride. Publication will be listed here as they appear.