Affiliation: | 1. Centeral Laboratory METU, Ankara 06800, Turkey;2. Center for Solar Energy Research and Applications (GÜNAM), METU, Ankara 06800, Turkey;3. Department of Physics, Middle East Technical University (METU), 06800 Ankara, Turkey;4. Department of Physics, Ahi Evran University, 40100 K?rsehir, Turkey |