Dr. John Geisz is a principal scientist in the High Efficiency Crystalline Photovoltaics Group at NLR. He received his doctorate in chemical engineering from the University of Wisconsin (Madison) in 1995 under the supervision of Professor Thomas Kuech, studying OMVPE of III-V semiconductors for chemical sensor applications. His bachelor's degree in chemical engineering was earned from the University of Michigan (Ann Arbor). Geisz joined NLR in 1995 where he has been studying the OMVPE growth and characterization of a variety of III-V semiconductor materials for high-efficiency photovoltaic applications, including dilute nitrogen and boron containing III-V alloys, III-V growth on silicon, and lattice-mismatched growth. He has developed three- and four-junction inverted metamorphic concentrator solar cells and quantified the optical coupling between these junctions. His work includes the demonstration of several world-record-setting solar cell efficiencies. Geisz has collaborated with researchers from around the world and is an author of many scientific publications. He is a member of the executive committee of the American Association of Crystal Growth and has helped organize several crystal growth conferences.