Jeff joined the theoretical materials science group at Sandia National Laboratories, Livermore in 1987, where he developed and applied advanced electronic structure methods to understand semiconductor surfaces and interfaces. In 1989, he joined the semiconductor physics group at SNL-Albuquerque, where he pioneered the use of massively parallel computers to predict the electronic and optical properties of semiconductor interfaces, surfaces, and alloys. Much of his work focused on understanding the fundamental properties of phosphide- and nitride-based visible lighting emitting compound semiconductors. At SNL, he also led the Semiconductor Materials and Device Department that focused on R&D in compound semiconductors and nanoscale synthesis, characterization, and modeling of advanced materials. His group was the first to demonstrate high power UV light emitting diodes in the 350-380nm range, with applications in chemical sensing and white light generation. In 2000, he joined Uniroyal Optoelectronics (UOE) as the Chief Technology Officer. Subsequently, he was a consultant to DOE-EERE on the Solid-State Lighting Initiative, and co-founded Medical Lighting Solutions, a business focused on medical applications of LED technology. Jeff rejoined Sandia National Laboratories in 2004 to manage the Solar Technologies Department, which included R&D efforts in Photovoltaics and Concentrating Solar Power. Currently, Jeff is the senior manager of group 1880 and the Director of the Center for Integrated Nanotechnologies (CINT), one of five DOE-BES-SUFD Nanoscale Science Research Centers (NSRC). Jeff has authored over 80 scientific papers and conference proceeding papers and four US patents.