Financed scholarships:

• Time-resolved optical microscopy techniques to characterize 2D transition metal dichalcogenides
• Novel architectures for advanced sensing based on 2D materials platforms
• Coherent control of electronic dynamics in layered quantum materials
• Supersonic cluster beam synthesis of innovative transition metal oxides photoelectrodes for hydrogen production
• Biomolecule mapping and identification via optical microscopy techniques (BioMAP)
• Study of a real time inspection system based on infrared and THz to be combined with a multi-energy X-ray inspection system for food and automotive applications
• Biomarker sensing for precision medicine in digital healthcare
• Magnetic topological materials for caloritronics and quantum technologies
• Designing an evaluation framework for eXplainable Artificial Intelligence in Health care

Time-resolved optical microscopy techniques to characterize 2D transition metal dichalcogenides

Student: Lishin Thottathi

Background and motivation

2D transition metal dichalcogenides (TMDs) hold great potential for application in different fields, in particular in nanoelectronics and photonics. In nanoelectronics, large energy dissipation due to heating in chips is unsustainable in terms of both costs and performance drop and 2D TMDs hold great potential to alleviate these problems. In photonics, the integration of 2D TMDs is predicted to enhance the energy harvesting. Towards such applications, it is crucial to develop a controlled, engineered, synthesis at large scale of such materials with high uniformity and to investigate their electronic/optical/thermal dynamics. Among the TMDs, MoS2, MoTe2, WS2 and WTe2 and are the most attractive materials to be investigated. The aim of this project is to synthetize and characterize the 2D TMDs materials and develop ultrafast temporally and spectrally resolved high resolution optical microscopy methods to investigate the electronic and thermo-mechanical aspects of 2D TMDs deposited on a bulk substrate. The main aspects of the project are:

1. Synthesis of the 2D TMDs and characterization with spectroscopic ellipsometry.
2. Fast optical surface mapping in various environments (i.e. air and liquids) by microsphere assisted optical microscopy to get sensitivity to the few atomic layers constituting the surface termination;
3. Investigation of hot spots and dielectric spacers;
4. Use of neural networks and machine learning techniques to analyze experimental data.

Supervisors

Prof. Gabriele Ferrini, UCSC, gabriele.ferrini@unicatt.it
Dr. Alessio Lamperti, IMM-CNR, alessio.lamperti@mdm.imm.cnr.it
Prof. Valeri Afanasiev, KU-Leuven, valeri.afanasiev@keuleuven.be

Novel architectures for advanced sensing based on 2D materials platforms.

Student: Michele Zanotti

Background and motivation

Among forefront applications of 2D materials such as graphene (GR) and transition metal dichalcogenides (TMDs) the detection of sub-ppm concentrations of small molecules on a background of strongly interfering gas mixtures is currently challenging physics, chemistry and device engineering and requires an in-depth knowledge of molecule-surface interactions at the nanoscale. These materials provide a unique opportunity to discover new sensing layers either through functionalization of single 2D layers or through a combination of 2D layers of different compounds to obtain novel heterostructures.

In this project, platforms based on properly functionalized 2D materials will be developed to produce arrays of miniaturized sensors for applications in the field of volatolomics, i.e. the profiling of VOCs emitted by living organisms, which is taking an increasing importance in various scientific areas such as medicine, as well as food and environmental sciences.

Bridging surface chemistry with device engineering, this project is aimed to develop ultra-sensitive arrays of sensing layers for the detection of biomarkers of lung pathologies in the exhaled breath. Layers characterization will involve photoemission and Raman spectroscopies, along with scanning probe spectro-microscopies. All materials will be functionalized at the nanoscale with selected molecules to make them more selective to specific target molecules. Data analysis with machine learning methods will be used to discriminate potential pathologies through pattern recognition in molecular fingerprint of breath samples.

Supervisors

Prof. Luigi Sangaletti UCSC, Italy, luigi.sangaletti@unicatt.it
Prof. Steven De Feyter, KU Leuven, Belgium, steven.defeyter@kuleuven.be

Coherent control of electronic dynamics in layered quantum materials (Co-financed by PRIN)

Student: Mohammadjavad Azarm

Background and motivation

Cooperative effects induced by light-matter interactions have been studied for decades. These studies have focused on atomic and molecular systems and have led to spectacular experimental findings in the realm of cavity quantum-electrodynamics (QED). In standard cavity-QED, direct interactions between matter constituents are often weak and can be neglected. In this case, collective effects are solely due to effective interactions, which emerge from the microscopic interactions between matter constituents and a common cavity mode. Recent experimental advances have made it possible to monolithically integrate graphene and other two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs) or 2D oxides, with optical microcavities, paving the way for fundamental studies of cavity QED at the nanometer scale with 2D materials as the active medium. Here, in stark contrast to ordinary cavity QED of atomic and molecular systems, direct interactions between medium excitations (electrons, holes, and excitons) in 2D materials are strong and can be further enhanced by stacking 2D materials in a var der Waals (vdW) heterostructure.

The aim of this project is to investigate the main channels driving the electronic decoherence in layered quantum materials embedded in properly designed cavities and develop strategies and excitation protocols to preserve coherence and exploit coherent dynamics to enhance the physical properties of the material.

The PhD student will develop a coherent 2-dimensional electron spectroscopy (2DES) experiment to investigate the decoherence dynamics of optical and electronic excitations in nanostructured correlated materials. 2DES measures the third-order material coherent polarization by exploiting two coherent phase-locked pulses acting as a pump, and a third pulse acting as a probe, allowing for simultaneous resolution of excitation and detection frequency axes with fs temporal resolution. 2DES thus allows to investigate not only the population relaxation time, but directly the decoherence time of relevant modes. 2DES will be used to probe the decoherence dynamics of light-induced exciton gases in 2D materials (TMDs and oxides). In particular, we will look for signatures of modification of the intrinsic decoherence dynamics driven by: i) coherent interactions within the exciton gas; ii) coupling of inter-layer excitonic modes in vdW heterostructures; iii) coupling to cavity modes.

A crucial challenge is related to the sample dimensions, which command spatial resolution, mandatory to perform 2DES on micrometer-sized samples, possibly embedded in cavities. Much of the initial experimental efforts will focus on the implementation of a microscopy measurement scheme, to be coupled to state-of-the-art 2DES setups available at Univrsità Cattolica del Sacro Cuore, providing few-micron spatial resolution while retaining the intrinsic temporal resolution (10-20 fs).

Supervisors

Prof. Claudio Giannetti, Università Cattolica del Sacro Cuore, Italy, claudio.giannetti@unicatt.it
Prof. J-P Locquet, KU Leuven, BE, jeanpierre.locquet@kuleuven.be

Supersonic cluster beam synthesis of innovative transition metal oxides photoelectrodes for hydrogen production (Supported by PNRR-DM351 2022)

Student: Skerxho Osmani

Background and motivation

The need for efficient devices converting renewable energies to fuels such as H2 may be tackled by photoelectrochemical water splitting: electron/hole pairs generated at two photoelectrodes (PE) drive the half-reactions producing H2 and O2. The state of the art PE built with ternary metal oxides (TMOs) like CuFe2O4 face major limitations like scant efficiency, photocorrosion and instability. They are ascribed to the low charge transfer induced by the small polarons due to the TMO hybrid valence band orbitals, and to the high recombination rate of charge carriers at the TMO surface and bulk states. Moreover, current PE lacks a comprehensive investigation of different TMO phases, stoichiometries and transport properties for sizes below 50 nm. The project strategy is to overcome the current limits by: 1) reducing the TMO sizes by producing PE of ZnFe2O4, CuFe2O4 and BiFeO3 with a nanogranular morphology (NG-TMO) at scales below 50 nm by supersonic cluster beam deposition (SCBD); 2) determining the PE morphological, optical and electrochemical behavior for three different NG-TMO compounds; 3) determining the PE transport behavior from the reaction kinetic constants (kt for the hopping process and kr for recombination process), as a function of TMO selected stoichiometries, phases and sizes.

The expected project breakthroughs are: 1) a new class of nanostructured PE for electrochemistry, NG-TMOs; 2) morphological, optical and stoichiometric properties correlation with PE thickness and annealing temperature; 3) Electrochemical properties correlation with the PE thickness and annealing temperature; 4) charge transport correlation with morphology, optical response, stoichiometry; 5) reveal the role of small polarons and surface recombination in NG-TMOs at scales below 50 nm.

The student will be tutored by three experienced tutors at the Università Cattolica (UCSC) for the PE synthesis and physical properties characterization, at the university of Padova (UPD) and university of Notre Dame (ND) for the PE electrochemical characterizations.

Supervisors

Prof. Luca Gavioli, UCSC, Italy luca.gavioli@unicatt.it
Prof. Prashant Kamat, ND, USA pkamat@nd.edu
Prof. Gian Andrea Rizzi, UPD, Italy gianandrea.rizzi@unipd.it

Biomolecule mapping and identification via optical microscopy techniques (BioMAP) (Supported by PNRR-DM352 2022)

Student: Meisam Sadeghpour Karimi

Background and motivation

The optical mapping of biomolecules is an important topic in modern biology and medicine. The ability to capture signatures from native microbial DNA molecules (without amplification or library preparation) or features connected to biomolecules associated with diseases enables a new way to analyze biological specimens.

This project is devoted to exploring the enhancement of the optical response of a biomolecule residing near a thin film (graphene/2D dichalcogenides), a metallic substrate, or a dielectric surface.

The general physical mechanism is described, in classical terms, as an energy transfer/interaction process involving near-fields that could change the excitation mechanisms and the emissive properties of the biomolecules. The induced energy transfer/interaction can be used as a mean to do confocal-based biomolecule mapping, either via fluorescence collection or analyzing the time-resolved response in a pump-probe experiment. Further options include using near-field probes. The actual implementation will make use of solid-state nanopore microscopy for biomolecule characterization.

The metagenomics research will be conducted at Perseus Biomics, a startup that concentrates on the analysis of the microbiome composition and dynamics for healthcare applications.

Supervisors

Prof. Johan Hofkens, KU Leuven, Belgium, johan.hofkens@kuleuven.be
Prof. Gabriele Ferrini, UCSC, Italy, gabriele.ferrini@unicatt.it

Study of a real time inspection system based on infrared and THz to be combined with a multi-energy X-ray inspection system for food and automotive applications (Supported by PNRR-DM352 2022)

Student: Rizwan Asif

Background and motivation

In the inspections for quality controls in real time, which are performed on the production lines of food companies, there is a growing need for real time systems capable of detecting the presence of foreign bodies inside the packaging. For some applications, such as bulk products such as fruits and vegetables, the combination of more traditional X-ray based inspection systems with infrared and thz region systems would lead to a revolution in real-time inspection. This type of combined system would greatly increase the efficiency and selectivity of the inspection process leading to large savings in terms of products withdrawn from the market and the sharp increase in consumer safety. The technology developed can then also be applied in other industrial areas and, in particular, in the automotive sector.

This project aims to develop, characterise and implement a thz spectroscopy system that will be combined with the X-ray system currently produced by Xnext. The project will be divided into several phases:

In the first phase the student will develop an experiment dedicated to the production and use of thz radiation, identifying the most useful range of frequencies/wavelengths for real-time inspection and select/design devices such as camera and optical illuminator, as well as studying the most suitable optical geometry. In the last phase, to be realized at the company Xnext, the student will implement the technique developed in combination with the X-ray systems developed by Xnext.

The success of the project will open a new path in the field of real-time inspection with repercussions in the food, automotive, Pharmaceutical and security industry.

Supervisors

Prof. Claudio Giannetti, Università Cattolica del Sacro Cuore, Italy, claudio.giannetti@unicatt.it
Prof. Wouter Saeys KU Leuven, BE, wouter.saeys@kuleuven.be

Biomarker sensing for precision medicine in digital healthcare (Supported by PNRR-DM352 2022)

Student: Michele Galvani

Background and motivation

The analysis and classification of food substances is one of the major perspectives for the development of electronic nose technology (e-noses). Market analysis indicates that the food (Food and Beverage) sector between 2020 and 2026 will exhibit the highest growth rate among sectors where electronic noses are typically applied.

Currently the electronic noses, available on the market and produced by several companies mainly European and North American find application in different areas of the food chain and in different sectors including that of analysis of dairy productsdairy products, sweeteners, drinks (tea, wine) meat and fish, fruit and vegetables, oil. In addition to near-infrared spectroscopic techniques, the electronic noses represent a class of versatile and relatively inexpensive instruments which are expected to develop not only in terms of market shares but also in terms of technology, driven by the ability to implement "machine learning" algorithms for the processing of collected data to refine the ability to classify and control products.

The research project aims to develop nanostructured carbon-based electronic noses (e-noses) to monitor the growth processes of aromatic plant crops in greenhouses. The data collected during the monitoring will allow a capillary and real-time control of the growth parameters, thus allowing:

1. optimum use of the resources (energy, water, chemicals) used in cultivation
2. product quality control
3. 3) the suppression of information intended to improve the yield of the accounts by increasing the degree of sustainability of the process

Supervisors

Prof. Luigi Sangaletti UCSC, Italy luigi.sangaletti@unicatt.it
Prof. Steven De Feyter, KU Leuven, Belgium, steven.defeyter@kuleuven.be

Magnetic topological materials for caloritronics and quantum technologies

Student: Rikkie Joris

Background and motivation

Heat is often seen as a detrimental issue for electronic devices. However, certain quantum materials have a unique ability to convert heat into an electrical signal that is highly sensitive to magnetism. Since heat is related to vibrational modes of a crystal, this ability can translate into an ability to couple vibrational and magnetic degrees of freedom in such materials. This project is dedicated to such phenomena in thin films of a new class of quantum materials: magnetic topological insulators.

This project deals with the development of large area thin films of magnetic topological materials to study their fundamental properties. Specifically, we aim to synthesize MnBi 2Te4, a magnetic topological insulator that hosts efficient heat-charge (caloritronic) and lattice-spin (magnetoelastic) coupling. Some of these properties rely on the pseudo-relativistic properties of electrons in MnBi2Te4 that can be tuned by controlling growth chemistry (at Notre Dame) and probed using various methods including synchrotron-based spectroscopies (KU Leuven).

This PhD project includes a stay of one year at the University of Notre Dame, where the student will further develop the synthesis of MnBi2Te4 and Mn(Sb,Bi)2Te4 and their characterization, building on the experience of the Notre Dame group. The synthesis and characterization performed at Notre Dame is complemented by a set of experiments that the student will carry out at KU Leuven. Specifically, these experiments will include SQUID magnetometry, angle-resolved photoemission spectroscopy, X-ray magnetic circular dichroism, scanning tunneling microscopy and spectroscopy, magnetotransport, among others. At the KU Leuven, this project is embedded in a wide research program, where these and other topological materials are investigated as solid-state platforms for caloritronics and quantum applications.

Supervisors

Prof. Lino M. C. Pereira, KU Leuven, Belgium, lino.pereira@kuleuven.be
Prof. Badih A. Assaf, ND, US bassaf@nd.edu

Designing an evaluation framework for eXplainable Artificial Intelligence in Health care

Student: Ivania Donoso

Background and motivation

In recent years, we have witnessed the rapid adoption of AI to automate and solve different tasks. However, many of these systems do not explain their predictions to final users, which is critical in the healthcare domain. This problem has driven the development of eXplainable AI (XAI), and various methods have been proposed to construct explanations. One of the issues of current research in the area is that there is no widely adopted method to evaluate the goodness of these explanations. Most of the proposed systems are assessed using tailor-made questionnaires, and there is no unique set of metrics to compare methods. This research aims to close this gap by proposing an evaluation framework of XAI methods in supervised learning. We expect that this framework will make XAI research more scalable, and by doing so, AI systems will be adopted with confidence in the healthcare domain.

Supervisors

Prof. Denis Parra, PUC, Chile, dparra@ing.puc.cl
Prof. Katrien Verbert, KU Leuven, Belgium, katrien.verbert@cs.kuleuven.be