Dr. Richard K. Ahrenkiel is a Research Professor of Metallurgical and Materials Engineering at the Colorado School of Mines in Golden, Colorado. He is also a Consultant and Research Fellow Emeritus at the National Renewable Energy Laboratory (NREL), where he worked from 1981 to 2005. Prior to NREL, he worked at Eastman Kodak Research laboratories, and at the Los Alamos National Laboratory. Dr. Ahrenkiel’s area of specialization is the measurement and characterization of photovoltaic cells and materials, and he is one of the world experts in the area of carrier recombination and carrier lifetime. He invented a unique technique for measuring the excess carrier lifetime in materials. This technique, named Resonance-coupled photoconductive decay (RCPCD), has been extensively applied to silicon and non-silicon materials. Dr. Ahrenkiel received a B.S. degree in Engineering Physics and his M.S. and Ph.D. degrees in Physics at the University of Illinois, Urbana.