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Richard Ahrenkiel — Research Fellow Emeritus

Dr. Ahernkiel's area of specialization is the measurement and characterization of photovoltaic cells and materials. 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.

Dr. Richard K. Ahrenkiel is a Research Fellow Emeritus of the National Renewable Energy Laboratory (NREL) and Research Professor of Metallurgical and Materials Engineering at the Colorado School of Mines in Golden, Colorado.

His 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 has invented a unique technique for measuring the excess carrier lifetime in materials. The latter has been named Resonance-coupled photoconductive decay (RCPCD), and has been extensively applied to silicon and non-silicon materials. He has set up a version of the RCPCD measurement apparatus at the Colorado School of Mines.

Dr. Richard Ahrenkiel also works in photovoltaic device design and modeling. He has specialized in laser scribing of photovoltaic devices during the last year. The laser-scribing work has focused on thin films such as amorphous silicon and transparent conducting oxides.

Dr. Richard 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.

Recognition and Honors

Fellow of the American Physical Society

Life Fellow of the IEEE

Fellow of the American Vacuum Society

Fellow of the Optical Society of America

Hubbard Award Winner for Contributions to Photovoltaics (1998)

Research Fellow (NREL, 2000)

Selected Publications

RK Ahrenkiel, SW Johnston, D Kuciauskas, J Tynan, "Dual-sensor technique for characterization of carrier lifetime decay transients in semiconductors", Journal of Applied Physics 116 (21), 214510 (2014)

J. Moseley, M.M. Al-Jassim, H.R. Moutinho, H.L. Guthrey, W.K. Metzger, R.K. Ahrenkiel, "Explanation of red spectral shifts at CdTe grain boundaries", Applied Physics Letters 103 (2013)

Richard K Ahrenkiel, "Resonant Coupling For Contactless Measurement of Carrier Lifetime", J. Vac. Sci. Technol. B 31, 04D113

R. K. Ahrenkiel, A. Feldman, J. Lehman, and S. W. Johnston, "Novel Free-Carrier Pump-Probe Analysis of Carrier Transport in Semiconductors", IEEE Journal of Photovoltaics 3. Pp. 348-352 (2013)

R.K. Ahrenkiel, N. Call, S.W. Johnston, W.K. Metzger, "Comparison of techniques for measuring carrier lifetime in thin-film and multicrystalline photovoltaic materials", Solar Energy Materials and Solar Cells 95 (2010), 2197-2204

R. K. Ahrenkiel and S. W. Johnston, "An optical technique for measuring surface recombination velocity", Solar Energy Materials and Solar Cells 93 (2009), 645-649

R. K. Ahrenkiel and S. W. Johnston, "Interaction of microwaves with photoelectrons in semiconductors", Journal of Vacuum Science & Technology B (Microelectronics and Nanometer Structures), v 26, n 4, p 1508-15, July 2008

R. K. Ahrenkiel and S. W. Johnston, "Lifetime analysis of silicon solar cells by microwave reflection, Solar Energy Materials and Solar Cells, 92, pp. 830-838 (2008)

R. K. Ahrenkiel, S. W. Johnston, W. K. Metzger, and P. Dippo, "Relationship of Band-Edge Luminescence to Recombination Lifetime in Silicon Wafers", Journ. Of Electronic Materials 37 pp. 396-402 (2008)

R. K. Ahrenkiel S. W. Johnston, J. D. Webb, L. M. Gedvilas, J. J. Carapella, and M. W. Wanlass, "Recombination lifetimes in undoped, low-band gap InAs(y)P(1-y)/In(x)Ga(1-x)As double heterostructures grown on InP substrates", Appl. Phys. Lett. 78, 1092 (2001)

W. K. Metzger, R. K. Ahrenkiel, J. Dashdorj, and D. F. Friedman, "Analysis of charge separation dynamics in a semiconductor junction" Phys. Rev. B 71, 035301(2005)

R. K. Ahrenkiel, W. Metzger, and D. F. Friedman, "Transport Properties of Ordered-GaInP/GaAs Heterostructures", Appl. Phys Lett. 85, 1733 (2004)

Metzger, W.K.; Albin, D.; Levi, D.; Sheldon, P.; Li, X.; Keyes, B.M.; Ahrenkiel, R.K.; Journ. Appl. Phys. 943549-55, (2003), "Time-resolved photoluminescence studies of CdTe solar cells"

R. K. Ahrenkiel, R. Ellingson, W. Metzger, D. K. . Lubyshev, and W. K. Liu, "Auger Recombination in Heavily Cardon-doped GaAs", Appl. Phys. Lett. 26, 1879 (2001)

R. K. Ahrenkiel and S. W. Johnston, "Injection Level Spectroscopy of Impurities in Silicon", Surface Engineering 16,54 (2000)

R. K. Ahrenkiel, R. Ellingson, S. Johnston, and M. Wanlass, "Recombination lifetime of In(0.53)Ga(0.47)As as a function of doping density", Appl. Phys. Lett. 72, 3470 (1998)

R. K. Ahrenkiel, S. P. Ahrenkiel, D. J. Arent, and J. M. Olson, "Carrier transport in ordered and disordered In(0.53)Ga(0.47)As", Appl. Phys. Lett. 70, 756 (1997)

M. L. Lovejoy, M. R. Melloch, M. S. Lundstrom, B. M. Keyes, and R. K. Ahrenkiel, "Temperature dependence of minority hole mobility in n+-GaAs measured with a new variable temperature technique, J. Electronic Materials 233, 669 (1994)

R. K. Ahrenkiel, (INVITED PAPER), "Measurement of minority-carrier lifetime by time-resolved photoluminescence", Solid State Electronics 35, 239 (1992)