The effect of Sn codoping on the local Co structural environments of (In0.95-xSnxCo0.05)2O3 thin films using x-ray absorption spectroscopy

The effect of Sn codoping on the local Co structural environments of the (In0.95-xSnxCo0.05)2O3 (x = 0, 0.02, 0.05, 0.08) films has been investigated in detail by x-ray absorption spectroscopy at Co K-edge and L-edge. The results show that the Sn codoping can remarkably influence the local Co structures of the films. For the films with low Sn concentration (x ≤ 0.02), most Co2+ atoms substitute for In3+ sites of In2O3 lattices, while a part of Co atoms form the precipitate of Co metal clusters. With further increasing Sn concentration (x > 0.02), the doped Co atoms are completely substitutionally incorporated into the In2O3 lattices. It can be concluded that the codoping of Co and Sn atoms forms p-n pairs of electronics and holes with opposite charge state, which can activate the substitution of Co atoms in In2O3 lattice and suppress the forming of metallic Co clusters. The p-n codoping method can provide a powerful guiding principle in designing the oxides based diluted magnetic semiconductors.