1. Photovoltaics Group, Anhalt University of Applied Sciences, Bernburger Str. 55, 06366 Köthen, Germany
2. Group μMD, Institute of Physics, Martin Luther University Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Saale), Germany
3. Fraunhofer Center for Silicon Photovoltaics CSP, 06120 Halle (Saale), Germany