Stephen Streiffer is the Deputy Laboratory Director for Science and Technology, Interim Associate Laboratory Director for Photon Sciences, and Director of the Advanced Photon Source at Argonne. The Photon Sciences directorate consists of the X-ray Science, Accelerator Systems and Advanced Photon Source Engineering Support divisions, which comprise the Advanced Photon Source (APS); and the Argonne Accelerator Institute. His active research projects focus on utilizing in-situ synchrotron X-ray methods to probe chemical vapor deposition of complex oxides as well as phase transformations and nanoscale size effects in ferroic thin films. He is also currently involved in in-situ synchrotron X-ray studies of the synthesis of InGaN heterostructures as part of an effort to expand the basic understanding of materials for energy-efficient solid state lighting. He has authored or co-authored more than 150 scientific publications and holds one patent.