Day 2 :
Université de Sherbrooke, Canada
Time : 10:25-10:50
Professor Jan J. Dubowski received his PhD degree in Semiconductor Physics from the Wroclaw University of Technology, Poland. He is a Canada Research Chair and a full professor at the Department of Electrical and Computer Engineering of the Université de Sherbrooke, Canada. He is a Fellow of SPIE – the International Society for Optics and Photonics (citation: “For Innovative methods of investigation of laser- matter interaction”). He has published over 200 research papers, reviews, book chapters and conference proceedings. He is an associate editor of the Journals of Laser Micro/Nanoengineering, Biosensors and Light: Science & Applications.
Etching of semiconducting materials at rates approaching atomic level resolution is of high interest to the advancement of technologies addressing fabrication of low-dimensional devices, tunability of their optoelectronic properties and precise control of device surface structure. The so- called digital etching that takes advantage of a self-limiting reaction has the potential to address some of these challenges. However, conventional applications of this approach proposed almost 30 years ago, require specialized and expensive equipment, which contributed to a relatively slow progress in penetration of digital etching to micro/nanofabrication processing schemes. We have observed that for photoluminescence (PL) emitting materials with negligible dark corrosion, it is possible to carry out PL-monitored photocorrosion in cycles analogous to those employed in digital etching. The advantage of this approach is that photocorrosion of materials, such as GaAs/AlGaAs heterostructures, could be carried in a water environment. This digital photocorrosion (DIP) process could be carried out in cycles, each approaching sub-monolayer precision. I will discuss fundamentals of DIP and, in particular, mechanisms responsible for achieving high-resolution etch rates of semiconducting materials. For instance, we have demonstrated a successful dissolution of a 1-nm thick layer of GaAs embedded between Al0.35Ga0.65As barriers in a 28% NH4OH:H2O, and we claimed that under optimized conditions a further enhanced resolution is feasible. The nm-scale depth resolution achieved with DIP and low-cost of the instrumentation required by this process is of a potential interest to specialized diagnostics, structural analysis of multilayer nanostructures and, e.g., revealing in situ selected interfaces required for the fabrication of advanced nano-architectures.
We have explored the sensitivity of DIP to perturbations induced by electrically charged molecules, such as bacteria, immobilized on semiconductor surfaces. Here, I will highlight our recent studies on detection of Escherichia coli and Legionella pneumophila bacteria immobilized on antibody functionalized GaAs/AlGaAs biochips. I will also discuss the application of this approach for studying antibiotic reactions of bacteria growing on biofunctionalized surfaces of GaAs/AlGaAs biochips.
National University of Singapore, Singapore
Time : 11:05-11:30
Dr. Hao GONG is a Full Professor of Materials Science and Engineering at National University of Singapore. He is also the coordinator of the transmission electron microscopy laboratory at Department of Materials Science and Engineering. His research interests include transparent oxide conductors and semiconductors (n-type and p-type), energy storage materials and devices (mainly supercapacitors), energy harvest materials and devices (mainly solar cells), gas sensors, functional thin film and nano-materials, materials characterization (mainly on transmission electron microscopy and electron diffraction). Dr. Gong received his B.S. degree in Physics at Yunnan University in 1982. He passed his M.S. courses in Yunnan University, carried out his M.S. thesis research work at Glasgow University, UK, and received M.S. degree of Electron and Ion Physics at Yunnan University in 1987. He then did his PhD at Materials Laboratory at Delft University of Technology, the Netherlands, and obtained PhD degree there in 1992. He joined National University of Singapore in 1992, and is currently full professor at Department of Materials Science and Engineering. He has published about 200 refereed papers in major international journals.
Nanomaterials have special properties, and have important applications in energy storage and many other devices. For energy storage, supercapacitors have attracted great interest and development. Supercapacitor have found a lot of applications in electric cars and other equipment. Different materials have been proposed and used for supercapacitors. In this presentation, high performance supercapacitors based on nanoscale Ni-based materials, which show very high specific capacitance and energy density, are focused. The energy storage performance of such materials and devices are examined and the very high energy storage ability is discussed. Energy storage performance, microstructure, morphology and surface area are found strongly related to Ni and Co oxide structures and morphologies, and the incorporation of some other active materials also enhance performance. 3D core-shell structures contributing to energy storage is presented and discussed. Charged small full supercapacitors prototype will be shown to light up bulb and turn fans for a long time in this presentation.