The invention of the transistor in 1947 inspired research in semiconductor materials other than germanium and silicon, including compound III-V "direct-bandgap" semiconductors that could efficiently emit light. It was a student of transistor-inventor John Bardeen, Nick Holonyak, Jr., who explored alloy engineering aspects of these compounds that eventually led to the first demonstration of a practical visible-spectrum light emitting diode (LED) in 1962. Since then, several compound semiconductor materials systems have been developed for LEDs, the most important of which is the (Al,Ga,In)N system which demonstrated blue-emitting LEDs for the first time and for which the Nobel Prize in Physics was awarded in 2014. This rather unusual material system is now the backbone of solid-state lighting, which has transformed the flat-planel display industry, and has now penetrated about 50% of the traditional (i.e., incandescent, fluorescent, discharge) general lighting market, delivering enormous savings in energy consumption. This seminar will tell this story, including details of III-Nitride optoelectronic device physics, and look at what we might expect in the future for III-Nitride based photonic devices and their applications.
Dr. Mike Krames has more than 25 years of compound semiconductor materials, device, and applications experience, with emphasis on light-emitting diodes (LEDs) and laser diodes. He is currently president of Arkesso, LLC, a consulting firm in Silicon Valley focusing on wide bandgap semiconductor materials, devices and applications. Dr. Krames' previous roles include Chief Technology Officer of Soraa Inc., and Executive Vice President of Advanced Laboratories at Philips Lumileds (previously Lumileds Lighting, a joint venture between Hewlett-Packard Company and Royal Philips Electronics). He also has served on numerous advisory boards and boards of directors. His core expertise is in visible-spectrum compound semiconductor optoelectronic materials and devices. Dr. Krames played a key role in the launch of the first high-power LED platform for illumination (LUXEON®) and has made many contributions to the advancement of LED technology for solid state lighting in the areas of III-nitride epitaxy, device physics, emitter design, down-conversion materials, and applications. Dr. Krames has published over 80 papers and has been granted over 100 U.S. patents. He holds M.S. and Ph.D. degrees in Electrical Engineering from the University of Illinois at Urbana-Champaign, and is a Distinguished Alumnus with a B.S. degree in Electrical & Computer Engineering from the University of Texas at Austin. He is Chair of the LED Conference at SPIE Photonics West and is a Fellow Member of IEEE.