We consider the impact of a buffer layer on the net ionized carrier concentration and electron states in CdTe absorber in thin film CdS/CdTe solar cells. When compared to the solar cells employing ZnO buffer layers, in the cells formed on ZnSe and ZnS the Fermi level and the position of the dominant deep trap levels were observed to shift closer to the midgap of CdTe. This behaviour could be explained invoking possibility for the Cd vacancy defect clustering in CdTe:Cl. ; Comment: This paper is in preparation for a submission