Effect of the oxygen absorption on properties of ITO layers

Abstract The properties of thin indium-tin-oxide (ITO) layers prepared by a magnetron reactive sputtering from an 90% In+10% Sn target in an Ar+O2 atmosphere can be substantially modified by post-deposition annealing. Besides crystallization of the ITO layers we also found that diffusion of the oxygen atoms into and out of ITO layers changed their conductivity and transparency. The process of crystallization is irreversible, in contrast to the process of oxygen diffusion which is reversible. The ITO layers have a cubic structure with a space order corresponding to group Th7 (la3). The oxygen atoms diffusing into the layers cause deformation of the lattice and result in an increase of the lattice parameter up to 1%. The layers behave like degenerate semiconductors. The absorption edge is about 4 eV. Some properties of ITO layers as functions of the layer thickness are presented.