Kwantum-vastestoffysica
KU Leuven
Leuven
10 uur geleden

You will be part of the division for Quantum Solid-State Physics (QSP) at the department of Physics and Astronomy of the KU Leuven (https : / / fys.

kuleuven.be / qsp). KU Leuven, established in 1425, ranks number 45 on the Times Higher Education list. Moreover, according to the Reuters ranking, it is the seventh most innovative university worldwide (number one in Europe, after six American universities).

You will join several other postdoctoral researchers, PhD students and staff carrying out experimental research on condensed matter physics.

You will work in the state-of-the-art Flemish Atom Probe Microscopy facility (http : / / www.apt-flanders.be / ), located in the Leuven NanoCentre (https : / / set.

kuleuven.be / chemtech nanocentre). Besides having access to a wide range of in-house experimental facilities for sample fabrication and characterization, the project is situated within a collaboration with the Conformal Coating of Nanomaterials (COCOON) research group from UGhent (https : / / www.

ugent.be / we / solidstatesciences / cocoon / en).

We are looking for a highlydriven candidate, motivated to work in an international research team.

Candidates must hold a Master’s degreein Physics, Engineering or Nanotechnology, with a strong background insolid-state physics.

Interest and strong background on computer programming andsimulation will be regarded as highly advantageous.

Proficiency in the Englishlanguage is also required, as well as good communication skills, both oral andwritten.

Oxide materials, such as (doped)ternary oxides and perovskites, serve a broad spectrum of applications such as photovoltaicsand flexible electronics, battery or ferroelectric memory applications.

Irrespectiveof the application, the functionality in these materials is determined by theirstructural and chemical properties, often down to the atomic level, where a fewmissing oxygen atoms or their misplacement in the volume could have a drastic effect.

Hence, measuring and meticulously controlling these properties must gohand-in-hand.

Atomic Layer Deposition (ALD) isone preferred method to produce materials in a well-controlled fashion as itoffers the required atomic scale control on the layer thickness and composition.

Yet, atomic layer deposition of oxide materials remains challenging due totheir chemical complexity, which requires a variety of chemical reactions duringdeposition.

Measuring the final material composition and elemental distributionremains therefore a crucial counterpart. In most applications, these materialsare present as very thin layers or at buried interfaces, which calls for acharacterization technique that offers high spatial (near-atomic) resolution, asensitivity to probe low elemental concentrations and that can probe severalnanometers below the surface.

In this respect, Atom probe tomography (APT) hasemerged in the last years as a very promising analytical technique that satisfiesthese requirements.

Atom probe tomography is based onthe concept of the controlled field emission of atoms from a DC-biased (1 10kV) needle-shaped specimen (radius < 100 nm).

A time-resolved voltage or a laserpulse superimposed on the DC bias allows for mass identification via time-of-flight detection, withthe aim to determine the mass and original location of each atom in the evaporated volume.

Ultimately, a 3-dimensionalatom map is created from which the local elemental composition can beinvestigated, addressing questions such as uniformity at the nanoscale, elementmigration and segregation, formation of atomic clusters, etc.

Notwithstanding its experimentalsuccesses, the fundamental physics of laser-assisted APT analysis of oxides isstill poorly understood and suffers from artefacts, limiting quantification andspatial accuracy.

One of the most intriguing pending questions is the fact thatfield-evaporation is facilitated by a laser pulse with photon energies whichare (significantly) smaller than the oxide (wide) bandgap whereby no lightabsorption is expected to occur.

In this project, the PhDcandidate will be placed at the crossroads between the functional properties ofcomplex oxides, their atomic scale synthesis through ALD and the atomic scalecharacterization through APT, with the latter being the main angle of approach.

The uniqueness of this project lies in its synergistic approach of using APT toexplore the link between atomic scale ordering and the functionality of the ALDfabricated oxide, and, vice versa, using the atomic scale control offered bythe ALD technique to create unique model systems to investigate the underlying physicsof APT.

To tackle this, you will have the possibility to explore an extensivescientific playground, including experimental work (ALD growth, specimenpreparation, APT experiments.

  • data analysis (3D reconstruction andanalysis) and physical modelling (theoretical and through simulations,regarding the laser interaction with nano-objects, spatio-temporal evolution ofelectric fields and temperature...).
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