Abstract: X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) were combined to study the effect of (Cr, Cu, Li) codopants on the distribution of magnetic Co atoms in Co-doped ZnO thin films. For the single-doping of Co in ZnO, there are two occupation sites of Co in ZnO: the substitutional sites for Zn and metallic Co clusters. After Cr doping, the metallic Co clusters vanish and all the Co atoms occupy the substitutional sites. On the contrary, Cu(Li)-codoping further increases the content of metallic Co clusters. In-depth analysis suggests that the distinct roles of Cr and Cu(Li) codopants for mediating the distribution of Co atoms in ZnO are intimately related to the occupation sites of codopants.

Key words: X-ray absorption fine structure (XAFS), codoping, Co-codoped ZnO