Dr. Iver Lauermann
(Dr. Iver Lauermann, Helmholtz-Zentrum Berlin für Materialien und Energie, Institut für Heterogene Materialsysteme, E-IH , Germany)
Spectroscopic methods based on synchrotron radiation yield valuable information on surface, interface and bulk composition as well as on the local chemical environment of compound semiconductor thin film solar cells and their components. This knowledge is necessary to understand these photovoltaic devices, which consist of stacks of at least five different materials, and improve them in a systematic way.
In this presentation we show some x-ray based state-of-the-art methods for the analysis of polycrystalline materials and entire photovoltaic devices and their limitations. Using results obtained with the “CISSY” end station at the BESSY II synchrotron in Berlin, Germany, we show how surface sensitive synchrotron excited photoelectron spectroscopy (XPS) and soft X-ray emission spectroscopy (XES) and x-ray absorption spectroscopy (XAS), which yield compositional and chemical information well beyond the depth sensitivity of XPS up to a micrometre scale, have increased our knowledge of the chemistry of surfaces and “hidden” interfaces of these systems. The CISSY end station allows in-system sputter deposition of buffer and window materials as well as wet-chemical surface modification and material deposition in an attached glove-box with a subsequent contamination-free transfer into the ultra-high vacuum analysis chamber.
Biography of Dr. Iver Lauermann
Dr. Iver Lauermann studied chemistry in Hamburg (Germany) and Southampton (UK). From 1987 to 1991 he was a research associate and doctorate student at the Institute for Solar Energy Research (ISFH) in Hannover (Germany). He graduated with Rüdiger Memming in the field of photoelectrochemistry of silicon carbide. After postdoctoral studies at the California Institute of Technology in Pasadena (USA), he worked as department head at the Institute for Applied Photovoltaics in Gelsenkirchen (Germany) and has been at the Helmholtz-ZentrumBerlin für Energie und Materialien (HZB) in Berlin (Germany) since 2002. His area of activity is the characterization of thin film solar cells and their components by means of synchrotron-based spectroscopy. He was involved in building the CISSY end station which is used for x-ray or UV photoelectron spectroscopy (XPS, UPS) using laboratory sources; plus X-ray emission spectroscopy (XES) and x-ray absorption spectroscopy XAS when connected to a synchrotron beamline. He has 12 years of experience in compound semiconductor thin film research, x-ray based analysis and use of synchrotron radiation, participated in national and European projects (ATHLET, currently SOPHIA, KESTCELLS) and is head of the CISSY Group at the institute for heterogeneous material systems (HZB).