FABILIS Research

Our research is based on Ionic Liquid Ion Sources (ILIS). ILIS are electrospray devices that produce ion beams by means of field evaporation from ionic liquids.

What are Ionic Liquid Ion Sources (ILIS)?

Ionic liquids are room temperature molten salts, or mixtures of cations or anions that are liquid at room temperature with no intervening solvent. You can think of it as a plasma in a bottle. The cations are usually large organic molecules, while the anions may be complex organic or simple inorganic ions. Ionic liquids have attracted much interest in energy storage and electrochemical synthesis, thanks to their stability, non-volatility, appreciable electrical conductivity, large electrochemical windows, and their suitability as solvents.

Example of an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate.

In ILIS, a micro‑tip emitter is covered with ionic liquid and biased to a high voltage with respect to a downstream metallic extractor. The electric field causes the liquid to deform into a sharp meniscus. At the apex of the meniscus, the electric field is high enough to trigger evaporation of ions from the liquid. The resulting beam can be used to treat materials.

Basic ILIS configuration, and scanning electron micrographs of an ILIS emitter microtip made of porous carbon xerogel.

Why ILIS for nanomanufacturing?

ILIS are amenable for focusing, so could be implemented in focused ion beams (FIB), a tool ubiquitous in nanotechnology for fabrication and characterisation.
ILIS are versatile – we have access to positive and negative ions, as well as many ion chemistries.
We can optimise the choice of liquid for the particular application.
Fast etching has been demonstrated with ILIS, thanks to the reactivity of the ions in the beam.

a Some examples of the many ions available with ionic liquids. b ILIS are used to irradiate different targets, which are covered by a copper grid which acts as a mask. c After irradiation, the grid pattern has been transferred to a silicon sample, and profilometry shows the irradiation has resulted in etching. — (a) Some examples of the many ions available with ionic liquids. (b) ILIS are used to irradiate different targets, which are covered by a copper grid which acts as a mask. (c) After irradiation, the grid pattern has been transferred to a silicon sample, and profilometry shows the irradiation has resulted in etching.

Our Work - Four Areas of Research

Characterisation: Explore the range of ion species produced by ILIS and their interaction with different substrate materials.
High‑throughput material removal: Investigate multiplex arrays of ILIS for scalable processing and faster material removal.
Focused Ion Beams (FIB) based on ILIS: Design and construct a bespoke focusing column for ILIS beams and implement it in an existing FIB system.
Deposition: At sufficiently low beam energy, deposit thin films of ionic liquids to study ionic liquid interfaces and surface phenomena.

Key Publications

These early papers describe the foundational techniques behind our work.

Ion field-evaporation from ionic liquids infusing carbon xerogel microtips

C. S. Perez-Martinez, P. C. Lozano

Applied Physics Letters · 27 Jul 2015 · doi:10.1063/1.4927481

Development of ion sources from ionic liquids for microfabrication

Carla Perez-Martinez, Stéphane Guilet, Noëlle Gogneau, Pascale Jegou, Jacques Gierak, Paulo Lozano

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena · 01 May 2010 · doi:10.1116/1.3432125