Keynote Speakers

 Prof. Qixin Guo

Prof. Qixin Guo

Department of Electrical and Electronic Engineering,
Synchrotron Light Application Center, Saga University, Japan
Speech Title: Photoluminescence Characteristics of Rare Earth Doped Ultrawide Bandgap Semiconductors by Synchrotron Radiation Excitation

Abstract: Ultrawide bandgap (UWBG) semiconductors, including AlN, BN, diamond, and Ga2O3 are at the forefront of extensive research efforts, covering a wide spectrum of materials, physics, devices, and applications. Microscale light emitting diodes (μLEDs) have attracted significant attention for their applications in augmented and virtual reality displays. Achieving high pixel density, efficiency, brightness, stable emission, and full-color emission is crucial for μLEDs. However, realizing full color μLED display technology poses challenges due to conventional mass transfer processes necessitating the extraction and precise transfer of red, green, and blue μLED chips from different epitaxial wafers. Rare earth (RE) doped semiconductors, characterized by strong and sharp emission resulting from intra-4f-shell transitions in RE ion cores, hold promise for applications in color display and luminescence devices. Extensive efforts have historically been dedicated to achieving visible color emission using RE doped GaN. Reports suggest that the luminescence efficiency of dopant emissions could significantly improve with a ultrawide bandgap host.

We have shown clear observations of red, green, and blue emissions from Eu, Er, and Tm doped ultrawide bandgap Ga2O3 films, respectively. We have also observed that the normalized emission intensity of RE-doped Ga2O3 films exhibits smaller temperature variations compared to RE-doped GaN films. Investigating the optical luminescence phenomena of semiconductors provides valuable insights into both the host lattices and defects, offering essential information for enhancing growth processes. Synchrotron radiation emerges as an ideal excitation source for studying UWBG semiconductors due to its remarkable tunability of photon energy and high brightness. We have constructed the Saga University beamline BL13 at Saga Light Source (SAGA-LS), Japan, to serve as a platform for such studies. In this talk, we will present recent advancements in the luminescence experiment system and share related experimental findings on UWBG semiconductors at the conference.

Biography: Prof. Dr. Guo received B. E., M.E., and Dr. E degrees in electronic engineering from Toyohashi University of Technology in 1990, 1992, and 1996, respectively. He is currently a Professor of Department of Electrical and Electronic Engineering, Saga University and was the Director of Saga University Synchrotron Light Application Center in Japan from April 2012 to March 2022. His research interests include epitaxial growth and characterization of semiconductor materials. Prof. Guo has published more than 380 papers in scientific journals including Nature Communications, Advanced Materials, Physical Review B, and Applied Physics Letters with more than 10,000 citations (h-index: 53). He is ranked as world top 2% scientists by Stanford University.

Prof. Sigitas Tamulevičius

Prof. Sigitas Tamulevičius

Institute of Materials Science,
Kaunas University of Technology, Lithuania
Speech Title: Production, Optical Studies and Applications of Metasurfaces

Abstract: The field of plasmonics broadly encompasses the interaction of light with metal nanostructures and, during recent years, has generated a lot of interest. Metal nanoparticles can resonate with light if their frequency matches the natural electron plasma oscillation, invoking a localized surface plasmon resonance (LSPR). This resonance can be further modified through hybridization with photonic modes when the nanoparticles are arranged in regular arrays exhibiting the collective response - surface lattice resonance (SLR). Moreover, these ultrafast processes can manifest themselves at the photonic length scale in arranged nanoparticle lattices.

In the current work the recent research results on the optical studies of colloidal solutions of silver and gold nanoparticles, production of metasurfaces (regular two-dimensional nanostructures) employing capillarity assisted particle assembly (CAPA) as well as studies of surface lattice resonance (SLR - mixed mode of LSPR and light diffraction in a regular structure) will be presented and discussed. The steady state light absorption measurements performed together with ultrafast transient pump-probe spectroscopy enabled to define spectral response as well as kinetics of the processes on the picosecond time scale. The ultrafast electron-phonon (e-ph) coupling relaxation processes for different average sizes and crystallinity of chemically synthesized silver nanoparticles were evaluated utilizing transient absorption spectroscopy. These issues are important in various fields of applications, including development of smart sensors exhibiting high sensitivity, as well as nanolasers. As an example, we present a comprehensive theoretical and experimental study of wavelength-tailored SERS substrates with improved sensitivity, exploiting surface lattice resonance in a plasmonic lattice comprised of CAPA-assembled Ag nanoparticles. Furthermore, we compared monomer and tetramer unit cell cases and found that the combined effect of tuned SLR and hot spots improves the enhancement factor more than 400 times over a substrate with a random layer of nanoparticles. The developed sensor was applied for the real-time leakage detection of electrolyte in lithium ion batteries.

Keywords: Noble metal nanoparticles, metasurfaces, surface lattice resonance

Acknowledgements: This research was performed within a project NANOTRAACES under the M-ERA.NET scheme and was funded by the Research Council of Lithuania, agreement No. MERANET-22-2,

Biography: Prof. Dr. Sigitas Tamulevičius obtained a Physics Engineer degree from the Moscow Engineering Institute of Physics (Moscow, former USSR) in 1979, a Ph.D. degree from the University of Vilnius in 1984, Doctor Habilitus degree from Kaunas University of Technology (1994). From 1990 to 1991, he was a postdoc at the Royal Institute of Technology (Stockholm, Sweden). In 1994 he was a Research Scholar, Fulbright Scholarship, Department of Physics, Massachusetts Institute of Technology (USA). Since 1996, he is a full professor in the Physics Department and Research director of the Institute of Materials Science of Kaunas University of Technology. He has co-founded a spin-off company and co-authored approx. 250 peer-reviewed publications in the field of vacuum and plasma technologies and optical technologies and spectroscopy with more than 3600 citations in Web of Science (h-index: 29), and is (co-) author of 15 textbooks on different aspects of Materials Science. Since 2002 he was a Member expert and since 2010 he is a Full Member of the Lithuanian Academy of Sciences. Prof. Sigitas Tamulevičius has received a series of awards including the Soros Foundation Research Grant, (1993) (Awarded by American Physical Society), Fulbright certificate (1997), National Award for Science (2000 and 2019), Recognition letter by the President of EMRS (2010), Honorary Professor of Southern Denmark University (2016), Laureate of Kaunas City Scientist Award (2017). He is Editor in Chief of the Scientific Journal “Materials Science (Medžiagotyra)", Member of the Editorial Board of “American Journal of Nanomaterials“ (Science and Education Publishing), “Coatings” (MDPI), member of the steering committee of European doctoral network Physics and Chemistry of Advanced Materials. He was a national representative in the FP7 program “Nanosciences, nanotechnologies, materials and new production technologies”. He headed multiple research projects funded by FP, Horizon 2020, COST, Eureka, NordForsk, Lithuanian State Foundation for Research and Studies, the Research Council, as well as Science and Innovation Agency of Lithuania. 18 Ph.D. theses were defended under his guidance; he has supervised six postdoctoral researchers.

Prof. Faiz Shaikh

Prof. Faiz Shaikh

School of Civil and Mechanical Engineering,
Curtin University, Australia
Speech Title: Fresh, Mechanical, and Microstructural Properties of Concrete Containing Lithium Slag (Lithium Refinery Residue)

Abstract: In this study, fresh properties, mechanical, and microstructural properties of 0–60 % cement replaced lithium slag (LS) concretes were thoroughly determined with a total binder content of 400 kg/m3 and water-binder ratio of 0.435, and the properties were compared with the same mix proportion of FA concrete. The results show that 20–60 % LS concrete mixes produced normal density concrete within the design slump of 125 ± 25 mm and air content of 2 ± 0.5 %. At 90 days, the average compressive strength, tensile strength, and elastic modulus of 40 % LS concrete were 58.6 MPa, 4.10 MPa, and 39 GPa, respectively, which are higher compared to 40 % FA concrete of 35.5 MPa, 3.0 MPa, and 31.1 GPa, respectively, revealing that LS concrete offers better mechanical strength. However, mechanical strengths decreased significantly beyond 40 % LS incorporation. The experimentally determined 28 days mechanical strengths of 40 % LS concrete were underestimated by ACI 318 and AS 3600 standard equations. The BSE-EDS on the ITZ of fine and coarse aggregate confirmed a consistent development of amorphous and amorphous intermediate hydration products in the development of mechanical properties of LS concrete mixes.

Biography: Prof. Faiz Shaikh received his Ph.D. degree in civil engineering from the National University of Singapore (NUS) in 2005. Since 2009, he has been with Curtin University, Australia. He is a Chartered profession engineer (CPEng.) of Australia, fellow of Engineers Australia (FIEAust) and member of Concrete institute of Australia. Among much research interests the sustainable use of various industrial by-products in infrastructure application e.g. in low carbon concrete and fibre reinforced cementitious composites, pavement material, etc. is his one of the key research areas where he has contributed in terms of research publication, industry collaboration, training/mentoring of young engineers and success in research fund. He has successfully completed various research projects on the utilization of fly ash, blast furnace slag, ferro-nickel slag, lithium refinery residue and silica fume as partial replacement of cement in concrete; construction and demolition wastes, recycled glass aggregates, waste tyres crumb rubbers, copper heap leach residue as aggregates in concrete; and development of geopolymer concrete using fly ash or fly ash-slag blend or lithium refinery residue-fly ash. He has supervised 11 PhD and 3 MPhil students and currently supervising 6 PhD students.

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