SEMINAR: GaN Technology for Lighting and Power Applications
Conn Center for Renewable Energy Research
Dr. Balakrishnan Krishnan
of Research and Technology Services at BRIDG
The group III nitrides (AlN, GaN and InN) represent an important trio of semiconductors because of their direct band gaps which span the range 0.6-6.0 eV, including the whole of the visible region and extending well out into the ultraviolet (UV) range. They form a complete series of ternary alloys which, in principle, makes available any band gap within this range and the fact that they also generate efficient luminescence has been the main driving force for their recent technological development. High brightness visible light-emitting diodes (LEDs) are now commercially available, a development which has transformed the market for LED-based full color displays and which has opened the ways to many other applications. Key inventions during the development of blue LEDs and laser diodes (LDs) that led to lighting revolution will be discussed.
Power semiconductor devices based on silicon (Si) are quickly approaching their limits, set by fundamental material properties. Wide bandgap materials, such as, SiC and GaN have suitable properties for power electronic applications and are being pursued as better alternatives for Si under challenging conditions; however, fabrication of practical devices from these materials are challenging. SiC technology has matured to a point of commercialized devices, whereas GaN requires further research to realize full material potential. Manufacturing aspects of GaN based lighting and power devices will be discussed.
Biosketch: Dr. Krishnan has more than 25 years of research experience in various aspects of III-V and III-Nitride Semiconductors. After earning his Ph.D. in Semiconductor Physics (Crystal Growth and Characterization) from Anna University, India, in 1992, he moved to Japan and did extensive research on III-nitride & III-V epitaxy and devices. From 2007 until 2010 he served as a faculty at the University of South Carolina and during this period he continued to focus on MOCVD growth of nitride semiconductors and devices. Later, he worked as a Senior Research Scientist and Technology Lead at Veeco Instruments. As a part of his assignment, he collaborated with many of the world’s leading GaN based optoelectronic and electronic device manufacturers, and research institutions on MOCVD projects. He is also a consultant for Nitek Inc. and Alliance MOCVD. He is the author of 151 journal publications, 10 book chapters, and 264 conference presentations (including 30 invited lectures). He is a recipient of several awards and reviewer for many technical journals and is a member of many professional societies