Electron energy-loss spectroscopy analysis of the electronic structure of nitrided Hf silicate films

We have shown, using electron energy-loss spectroscopy, that incorporating N into a Hf silicate film reduces the band gap. We also experimentally clarified that the Hf atoms in the film are coordinated by N atoms, and we used ab initio electronic structure calculations to show that the Hf–N coordination can be a cause of the decrease in the band gap. Therefore, when a Hf silicate film is used as a gate dielectric in a metal-oxide-semiconductor field-effect transistor, N incorporation can affect the gate leakage current because the decrease in the band gap lowers the band offsets of the dielectric on Si.