A structural and compositional analysis of a TiO_x diffusion barrier for indium Tin Oxide/Si contacts

We investigated the structural and compositional changes of titanium oxides as a diffusion barrier between indium tin oxide (ITO) and Si under two different Ti oxidation conditions: (1) annealing of the Ti layer deposited on Si in air followed by ITO deposition (Type I) and (2) annealing in nitrogen after the deposition of ITO/Ti on Si (Type II). The diffusion barrier layer in both samples, namely the Ti layer oxidized under different conditions, consisted of two regions: a region composed of a mixture of suicide and titanium oxide near the Si substrate and a titanium oxide region near the ITO layer. However, the titanium oxide in the Type I samples was composed of TiO₂ and Ti ₂O₃ phases, whereas Ti₂O₃ was dominant in the Type II samples. In addition, the Type I and II samples showed the formation of voids in the middle of the barrier layer and in the region near the ITO layer, respectively. Therefore, the electrical and optical properties of ITO/ TiO_x/Si are dependent on the structural and compositional changes of the diffusion barrier layer.