• Sep-Okt 2005, Silicon Photovoltaic Department (SE1), Solar Energy Research Division, Hahn-Meitner Institute Berlin, Germany
  • Sep 2004, Silicon Photovoltaic Department (SE1), Solar Energy Research Division, Hahn-Meitner Institute Berlin, Germany
  • Aug-Okt 2003, Silicon Photovoltaic Department (SE1), Solar Energy Research Division, Hahn-Meitner Institute Berlin, Germany
  • May-July 2002, Silicon Photovoltaic Department (SE1), Solar Energy Research Division, Hahn-Meitner Institute Berlin, Germany
  • Aug-Oct 2001, Silicon Photovoltaic Department (SE1), Solar Energy Research Division, Hahn-Meitner Institute, Berlin, Germany
  • Sept-Nov 2000, Institute for Photovoltaic, Research Center Juelich, Germany
  • Aug-Oct 1999, Institute for Photovoltaic, Research Center Juelich, Germany
  • Sept-Nov 1998, Institute for Photovoltaic, Research Center Juelich, Germany
  • Sept-Nov 1997, Institute for Photovoltaic, Research Center Juelich, Germany
  • Jun-Aug 1996, Institute for Photovoltaic, Research Center Juelich, Germany
  • Jun-Aug 1995, Institute for Photovoltaic, Research Center Juelich, Germany
  • Jul-Sept 1994, Faculty of Physics, Phillips University Marburg, Germany