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Archive for the ‘Circuits & Devices’ Category

InAs Quantum Dot Micro-disk Lasers Grown on Exact (001) Si Emitting at Communication Wavelengths

Monday, May 29th, 2017

Wednesday May 31, 2017 at 2:10 p.m. Kei May Lau, Fang Professor of Engineering and Chair Professor at the Hong Kong University of Science and Technology will be presenting “InAs Quantum Dot Micro-disk Lasers Grown on Exact (001) Si Emitting at Communication Wavelengths”.

Day & Time: Wednesday May 31, 2017
2:10 p.m. – 3:00 p.m.

Speaker: Kei May Lau
Fang Professor of Engineering and Chair Professor
Department of Electronic and Computer Engineering
Hong Kong University of Science and Technology

Location: Room BA 1220
40 St. George Street
Toronto, ON M5S 2E4

Contact: Junho Jeong

Organizers: IEEE Toronto Photonics Society

Abstract: To support an energy-efficient optical interconnect technology enabled by silicon photonics, development of low-energy-consumption active devices and the corresponding integration technology is needed. Most communication wavelength lasers with excellent device performance have been grown on III-V substrates and bonded to silicon. For integration, there are considerable advantages in a technology that allow growth and fabrication of such lasers on III-V/ Si compliant substrates. Quantum dot (QD) active layers grown on lattice-matched substrates have already shown their capability for lasers with low-threshold densities and temperature-independent operation. In addition, the reduced sensitivity of QD to defects and their unique capability of filtering dislocations make them an ideal candidate as the gain medium of hetero-integrated III-V on Si optical sources. In this talk, I will discuss the growth of multi-stack QDs on compliant substrates by MOCVD. Fabrication and laser characteristics of whispering-gallery-mode (WGM) micro-disk lasers using the grown epitaxial structures will also be discussed. Initial demonstration was achieved using simple a colloidal lithography process in combination with dry and wet-etching. The micro-disk lasers were one to four microns in diameter, with single mode lasing at either 1.3 or 1.55 μm, depending on the barrier/cladding system. With smooth sidewalls and sufficient undercut by wet etching of the pedestal, the air-cladded MDs exhibit ultra-low thresholds of a few mW by optical pumping. Preliminary results of electrically-pumped micro-lasers will also be presented. These energy-efficient microlasers are excellent candidates for on-chip integration with silicon photonics.

Biography: Professor Kei May Lau is Fang Professor of Engineering at the Hong Kong University of Science and Technology (HKUST). She received the B.S. and M.S. degrees in physics from the University of Minnesota, Minneapolis, and the Ph.D. degree in Electrical Engineering from Rice University, Houston, Texas. She was on the ECE faculty at the University of Massachusetts/Amherst and initiated MOCVD, compound semiconductor materials and devices programs. Since the fall of 2000, she has been with the ECE Department at HKUST. She established the Photonics Technology Center for R&D effort in III-V materials, optoelectronic, high power, and high-speed devices. Professor Lau is a Fellow of the IEEE, and a recipient of the US National Science Foundation (NSF) Faculty Awards for Women (FAW) Scientists and Engineers (1991) and Croucher Senior Research Fellowship (2008). She is an Editor of the IEEE EDL and Associate Editor of Applied Physics Letters.

CMOS Bioelectronics

Tuesday, January 17th, 2017

Friday January 20, 2017 at 2:10 p.m. Professor Ken Shepard, Electrical and Biomedical Engineering at Columbia University, will be presenting “CMOS Bioelectronics”.

Speaker: Prof. Ken Shepard
Electrical and Biomedical Engineering
Columbia University

Day & Time: Friday, January 20th, 2017
2:10 pm – 3:00 pm

Location: Room GB 248, 35 St George St, Toronto, ON M5S 1A4

Contact: Junho Jeong

Organizer: IEEE Toronto Photonics Chapter

**Refreshments will be served**

Abstract: CMOS electronics, which has revolutionized communications and computation in the last 30 years, has the same transformative potential for life science applications with appropriate “more than Moore” augmentation. In this talk, we will outline work in my group over the last 10 years, which has applied augmented CMOS to problems in molecular diagnostics, microbiology, and neuroscience. We will discuss several on-going projects in my group in these areas include high-bandwidth CMOS-integrated nanopores, point-functionalized nanotube devices integrated on CMOS for genomic diagnostics, electrochemical imaging chips for understanding microbial communities, high-density electrophysiological arrays for in vivo and in vitro studies of neural systems, biologically powered solid-state electronics, and various wireless probes to studying neural and cellular systems.

Biography: Ken Shepard received the B.S.E. degree from Princeton University, Princeton, NJ, in 1987 and the M.S. and Ph.D. degrees in electrical engineering from Stanford University, Stanford, CA, in 1988 and 1992, respectively. From 1992 to 1997, he was a Research Staff Member and Manager with the VLSI Design Department, IBM T. J. Watson Research Center, Yorktown Heights, NY, where he was responsible for the design methodology for IBM’s G4 S/390 microprocessors. Since 1997, he has been with Columbia University, New York, where he is now the Lau Familty Professor of Electrical Engineering and Biomedical Engineering. He also was Chief Technology Officer of CadMOS Design Technology, San Jose, CA, until its acquisition by Cadence Design Systems in 2001. He is current serving on the board of two other start-ups, Ferric, commercializing integrated voltage regulator technology, and Quicksilver, commercializing single-molecule electronic genomic diagnostics. His current research interests include power electronics, carbon-based devices and circuits, and CMOS bioelectronics.

Quantum-confined oxide heteronanostructures: Low-cost design, electronic structure, interfacial properties & device applications for solar energy conversion

Saturday, June 18th, 2016

June 24, 2016 at 11:10 a.m. Professor Lionel Vayssieres, of Xi’an Jiaotong University, will be presenting “Quantum-confined oxide heteronanostructures: Low-cost design, electronic structure, interfacial properties & device applications for solar energy conversion”.

Speaker: Professor Lionel Vayssieres
International Research Center for Renewable Energy (IRCRE), Xi’an Jiaotong University

Day & Time: Friday, June 24, 2016
11:10 a.m. – 12:00 p.m.

Location: Room BA 1200
40 St George St, Toronto, ON M5S 2E4

Contact: Junho Jeong

Refreshments will be served prior to the lecture.

Abstract: Given that conventional technologies which attempt to improve the performance of existing materials and devices for solar energy conversion and solar fuels generation by further development along the same incremental approach are reaching their limits, it is crucial to develop novel materials where bulk limitations are overcome by changing the fundamental underlying physics and chemistry, by e.g. nanostructuring design and quantum confinement effects. As important is a comprehensive fundamental and applied knowledge of their interfacial properties and electronic structure in relation with their structural and optical properties to quantitatively optimize their efficiency. Our strategy to address such crucial requirements is to fabricate materials and devices based on metal oxide (hetero)nanostructures consisting of surface chemistry-controlled quantum dots and rods building-blocks utilizing low-cost and large scale aqueous chemical growth. The electronic structure and structural, optical, and photoelectrochemical properties of such novel visible light-active oxide semiconductors based on vertically oriented quantum rod-arrays have been thoroughly investigated at synchrotron radiation facilities by X-ray spectroscopies. Direct correlation between dimensionality and surface chemistry, bandgap and band edges, orbital character and symmetry, surfaces states, electrical and defect properties have been unraveled and will be demonstrated on various oxide structures of high relevance for this field. An overview of decades of achievements as well as recent advances in novel materials design strategy will be demonstrated along with the latest breakthrough in highly efficient structure for low cost solar hydrogen generation by direct water splitting at neutral pH using the largest free natural resources on Earth, e.g. the Sun and seawater.

Biography: Born in 1968, Prof. Vayssieres obtained a MSc in Physical Chemistry in 1990 and a PhD in Inorganic Chemistry in 1995 from the Université Pierre et Marie Curie, Paris, France for his research work on the Interfacial & thermodynamic growth control of metal oxide nanoparticles in aqueous solutions. He has been invited as a visiting scientist at: UT Austin; the UNESCO Centre for Macromolecules & Materials, Stellenbosch University and iThemba LABS, South Africa; the Glenn T. Seaborg Center, Chemical Sciences Division, at Lawrence Berkeley National Laboratory; Texas Materials Institute; The Ecole Polytechnique Fédérale de Lausanne, Switzerland; the University of Queensland, Australia, and Nanyang Technological University, Singapore. He was an independent scientist at the National Institute for Materials Science (NIMS), Tsukuba, Japan for 8 years. He has authored 100+ publications in major international journals and book series cited 9150+ times since the year 2000 (4500+ since 2011, Google Scholar); Top 1% Scientists in Materials Science (Thomson Reuters). All time 8 ESI Highly Cited papers (5 as first and corresponding author) in Materials Science, Chemistry, Physics, and Environment/Ecology. He has given 344 talks in 30 countries: 166 lectures at international conferences/workshops (45 plenary/keynote, 98 invited, 21 contributed, 2 tutorials) including one of the last MRS Spring Symposium X lecture held in San Francisco in 2015 as well as 178 seminars at universities, governmental and/or industrial research institutes. He is currently a full time 1000-Talent Professor, co-founder and scientific director of the International Research Center for Renewable Energy (IRCRE) at Xi’an Jiaotong University, China as well as, since 2003, a guest scientist at the Chemical Sciences Division at Berkeley National Lab and the founding editor-in-chief of the International Journal of Nanotechnology.