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Can Bayram

Can Bayram

University of Illinois at Urbana Champaign ,USA

Title: Gallium nitride compound semiconductors for ultraviolet, visible, and terahertz photonics

Biography

Can Bayram received the Ph.D. degree in 2011 from Electrical Engineering and Computer Science Department of Northwestern University, IL with a focus on Solid State and Photonics. His research interests focus on GaN technology and novel photonic devices. He is an expert in the development of InGaN-based visible light emitting diodes and high efficiency III-V solar cells, and interested in novel growth and fabrication technologies. He is the recipient of distinguished world-wide awards, has more than 100 scientific contributions,and an active reviewer for journals and agencies. He also serves on the conference program and fellowship committees regularly.

Abstract

Gallium Nitride (GaN)-based compound semiconductors, throughout their entire composition (tuned by varying the Aluminum (Al), Gallium (Ga), and Indium (In) elemental content), possess direct bandgap and their bulk-layer-spectrum can be tuned from deep ultraviolet (~200 nm) to near-infrared (~1700 nm). Furthermore, subband-energy engineering of AlGaN/GaNsuperlattice quantum structures enable the spectral response be pushed up to terahertz (~300 µm). As such, GaN-based photonic technology can be used in everyday to biotech and scientific applications including solid state lighting; detection of bio-agents/drugs/explosives; and optogenetics.In the first part of my talk, I will give a brief overview on band-to-band ultraviolet and visible spectrum light emitting diodes (LEDs) and will be discussing novel integration schemes of such LED technologies to bring affordability and further functionality.In the second part of my talk, I will be focusing on intersubbandinfrared to terahertz quantum devices. Terahertz (THz) spectrum offers promising scientific (e.g. cancer detection), industrial (e.g. product defect detection), and military (e.g. explosives detection) applications. Thus yet, generation of THz frequency is rather challenging as it lies at the cusp of electronic and photonic frequencies – creating the so-called “THz gap”. Large conduction bandoffset (~1.8 eV), large longitudinal optical phonon energy (~90 meV), and fast carrier dynamics (~ fs) of GaN compound semiconductors motivate for THz emitters. I will summarize recent intersubband device results (i.e. optical modulators and resonant tunneling diodes) and then move to discussing promising THz emitter schemes.In conclusion, with continuous developments from materials to devices, GaN-based compound semiconductors extend their unique photonic solutions from ultraviolet and visible wavelengths towards THz spectrum.