Zinc diffusion in polycrystalline Cu In,Ga Se2 and single crystal CuInSe2 layers

The diffusion behavior of Zn in solar grade Cu In,Ga Se2 CIGSe is found to be similar to that in epitaxial CuInSe2 CISe , which indicates that grain boundaries only play a minor role as segregation sites and fast transport pathways. The diffu sivity obeys the Arrhenius equation DZn 3.8 10 amp; 8722;3 exp amp; 8722;1.24 eV kB T cm2 s amp; 8722;1 . Surprisingly, the 65 Zn diffusion profiles obtained by the radiotracer technique exhibit anomalous shapes with a second maximum near the CI G Se substrate interface. The observations may be indicative of an interstitial substitutional diffusion mechanism