High thermostable and conductive niobium doped titanium oxide for the application to a diffusion barrier layer of silicon quantum dot superlattice solar cell structure

We investigated the durability of the transparency and the conductivity of TiO₂:Nb against the high temperature thermal annealing, and the potential as a diffusion barrier layer of phosphorous atoms for silicon quantum dot superlattice solar cells. The films were annealed at 900 °C for 30 minutes under the forming gas atmosphere. After the annealing, conductivity of the films was measured. The conductivity of 247 S/cm was achieved. And the films kept high transparency in the range above 600 nm. From the depth profiles of phosphorous measured by secondary ion mass spectrometry (SIMS), it was revealed that TiO₂:Nb works as a diffusion barrier against phosphorous impurity.