The 12th Global Conference on Materials Science and Engineering (CMSE 2023)

Abstract: For millennia, thousands of materials have been sourced, synthesized, developed and employed in the service of humans. Scholars grouped them to denote their historical significance, and to provide cumulative knowledge of enabling scientific principles and advances. Poly-disciplinary approach, which draws upon advances in diverse scientific fields, sets the stage for imagining future directions of materials, i.e. Living / Intelligent Materials and Sustainable Materials.

Sustainable materials foster a healthy living environment via circular economy and reduction of associated greenhouse gas (GHG) emissions, wastage, and resources depletion. They are purposely designed & selected with lower environmental footprint and social costs, and higher circularity while satisfying the cost as well as functional requirements. In other words, the sustainable materials are friendly to the Earth’s ecosystem and human health with high circularity performance. Living / intelligent materials are capable of sensing and processing external signals as well as internally generated signals, and produce optimized responses & behaviours. Shape memory materials, smart materials, piezoelectric materials, photoelectric materials, thermoelectric materials, smart hydrogels, and cells & microorganisms incorporated materials are examples to name a few.

This lecture seeks to describe and discuss the principles of sustainable materials as well as living materials while siting case studies and examples.

Biography: Professor Seeram Ramakrishna, FREng, Everest Chair is a world-renowned poly-disciplinary scholar at the National University of Singapore, NUS (https://cde.nus.edu.sg/mou-with-haulio-to-develop-smart-haulage-scheduler-copy/; https://www.linkedin.com/in/seeram-ramakrishna/). He is an elected Fellow of UK Royal Academy of Engineering (FREng); Singapore Academy of Engineering; Indian National Academy of Engineering; American Association for Advancement of Science (AAAS). He is also an elected Fellow of ASMInternational, ASME, FBSE, and AIMBE, USA; and IMechEand IoM3, UK. His publications to date have received 177 H-index and 153,804 citations. He is named among the World’s Most Influential Minds (Thomson Reuters); and the Top 1% Highly Cited Researchers in cross-field (Clarivate Analytics). Stanford University C-score ranks him among top six impactful researchers of the world in materials, biomedical engineering, and enabling & strategic technologies. He is the Director of Center for Nanotechnology and Sustainability. He served as NUS Dean of Engineering and University Vice-President of Research Strategy, which are ranked among the world’s top ten and twenty, respectively.

Abstract: Micro scale light emitting diodes (μLEDs) have been extensively studied for augment and virtual reality display applications. It is highly required that μLEDs have high pixels per inch, high efficiency and brightness, stable emission, and full color emission. However, the realization of full color μLED display technology has been challenging because conventional mass transfer processes require the extraction of red, green, and blue μLED chips from different epitaxial wafers followed by precision transfers. Full color LEDs can be fabricated by using GaInN with different indium concentration as luminescence layers. However, the emission wavelength is unstable due to its temperature dependence of bandgap.

Rare earth (RE) doped semiconductors, which exhibit strong and sharp emission due to intra-4f-shell transitions in RE ion cores, have potential applications in color display and luminescence devices. Historically, much effort has been made to produce visible color emission using RE doped GaN. It has been reported that the luminescence efficiency of dopant emissions could be highly improved with a wide bandgap host. Moreover, the wide bandgap semiconductors exhibit highly thermal and chemical stability, which make them ideal hosts for RE ions. We have demonstrated that red, green and blue emissions are clearly observed from the Eu, Er, and Tm doped Ga₂O₃ films respectively. We found that the normalized emission intensity of the RE doped Ga₂O₃ films has a smaller temperature variation compared to that of the RE doped GaN films and showed that the bandgap of the films can be increased by adding Al into the films. In this talk, we present on the structure, surface morphology and temperature dependence of the photoluminescence of the RE doped (AlGa)₂O₃ films. Recent progress on the properties of the full color LEDs by using Eu, Er, and Tm co-doped Ga₂O₃ films will also be reported.

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 370 papers in scientific journals including Nature Communications, Advanced Materials, Physical Review B, and Applied Physics Letters with more than 9300 citations (h-index: 49).