Richard Ahrenkiel is a Research Fellow and Team leader of the Electrooptical Characterization Team at the National Renewable Energy Laboratory in Golden, Colorado. He is an Adjunct Professor of Electrical Engineering and Computer Science at the University of Colorado, Boulder and an Adjunct Professor of Physics at the University of Denver in Denver, Colorado and Adjunct Professor of Physics at the Colorado School of Mines in Golden, Colorado. He supervises graduate students at all of the above institutions. He received the B.S. degree in engineering physics, and the M.S. and Ph.D. degree in physics at the University of Illinois, Urbana, Illinois. He has worked primarily in the area of semiconductor physics and devices, specializing in material and device characterization. His specialty is the measurement of minority-carrier and recombination lifetime by a variety of techniques. He is an author or co-author on approximately 225 publications, many of these being in the areas of semiconductor physics. He is the inventor or co-inventor on six patents. He has contributed to six technical books and is the co-editor of Semiconductors and Semimetals, V 39. He is a Fellow of the American Vacuum Society, a Fellow of the American Physical Society, a Fellow of the Institute of Electrical and Electronic Engineers, and a Fellow of the Optical Society of America. He consults in private industry in the areas of semiconductor technology.