Chebelew, Tesfaye2018-07-052023-11-092018-07-052023-11-092011-06http://10.90.10.223:4000/handle/123456789/6621Recent discovery of superconductivity in the Iron-based layered pnictides with transition temperature Tc ranging between 26 and 56K has generated enormous interest in the study of these superconductors. In Iron-based superconductors (Iron-based layered pnictides), superconductivity occurs on doping of either electrons or holes in the FeAs layers. The Iron Fe2+, forms tetrahedron with in the layers. This means that pnictides Fermi level is formed by 3dxy, 3dyz, or 3d zx orbitals. Very intriguing property of theses new compounds is the rather high exibility concerning elemental substitution, leading to several families of superconductors, termed '1111', '122','11' and so on, depending on the chemical composition. In this newly discovered Iron-based layered pnictides like cuprates, has triggered challenge towards understanding the pairing mechanism. In this work we analyze superconductivity of Iron-based superconductor. After reviewing the current nding on this systems, we suggest phonon-exciton combined mechanism to give a right order of supercoducting transition temperature Tc's for whole class of Fe based superconductorsenmechanism of SuperconductivityThesis