III-Nitride Semiconductor Photonics: Beyond LED Lighting
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To date, the global investment in III-nitride compound semiconductors (e.g., InN, GaN, AlN, BN and their alloys) has surpassed any other compound semiconductors and is only next to silicon. III-nitrides have become the backbone of the massive LED lighting. However, the performance of III-nitride photonic devices in the deep ultraviolet (UV) spectral range has been extremely limited, due to the presence of extensive dislocations and inefficient p-doping. We have recently demonstrated that, with the use of defect-free nanowire structures, electrically injected semiconductor lasers in the UV-B (280-315 nm) and UV-C (100-280 nm) bands can be achieved, for the first time. Such efficient solid-state deep UV light sources will eventually replace the low-efficiency mercury lamps for a broad range of applications, including water purification, sterilization, medical diagnostics, and bio-agent detection. In addition, III-nitrides are the only known material whose energy bandgap can straddle the redox potential of water under deep visible and near-infrared light irradiation. In 2011, we have demonstrated, for the first time, spontaneous overall water splitting on GaN nanowire arrays. We have further discovered that the quantum efficiency for overall water splitting and hydrogen generation on the emerging nanostructured photocatalysts can be dramatically enhanced by precisely tuning the surface Fermi-level. Such high efficiency photocatalysts offers an entirely new avenue for recycling anthropogenic carbon dioxide to renewable fuels and for the direct and efficient conversion of methane into high valued chemical products, one of the holy grails in chemical science. In this talk, the use of BN as a suitable template for the emerging two-dimensional (2D) materials, and the realization of efficient lasers and solar-to-hydrogen conversion based on 2D materials will also be discussed.
Zetian Mi is an Associate Professor in the Department of Electrical and Computer Engineering at McGill University. He received the Ph.D. degree in Applied Physics from the University of Michigan, Ann Arbor in 2006. Prof. Mi's teaching and research interests are in the areas of III-nitride semiconductors, nanowires, two-dimensional materials, Si photonics, artificial photosynthesis, and solar fuels. He has received many awards, including the Hydro-Québec Nano-Engineering Scholar Award in 2009, the William Dawson Scholar Award in 2011, and the Christophe Pierre Award for Research Excellence (Early Career) in 2012 at McGill University. He has also received the Young Investigator Award from the 27th North American Molecular Beam Epitaxy (MBE) Conference in 2010. Prof. Mi served as the Associate Editor of IEEE J. Lightwave Technol. as well as the chair and organizer of many international conferences regularly.