Effect of CdS on CuInSe2 structure and properties

Precise determination of unit cell parameters a and c, microstructural study and measurements of microhardness H, the Hall coefficient RH, electrical conductivity σ and the Seebeck coefficient S of polycrystalline alloys in the (CuInSe2)1−x–(CdS)2x system (x=0−0.07) were performed. It was established that solubility limits of CdS in CuInSe2 vary for samples subjected to different heat treatments and lie in the range of 0.025≤x≤0.04. A non-monotonic behavior of the concentration dependences of properties with extrema in the vicinity of x=0.01 was detected and attributed to the processes of collective interaction and possible ordering of impurity atoms. An inversion of the conductivity type from p to n already under introduction of the first portions of CdS (x=0.005) was observed. From the temperature dependences of RH two donor levels (with energies of ∼47 and ∼65 meV) created by CdS were determined. On the basis of temperature dependences of the Hall mobility μH a predominant contribution of the impurity scattering was detected.