The effect of nitrogen (N) incorporation into HfSiO on the electronic structure and band alignment of HfSiO films was investigated. N depth profile data obtained by medium energy ion scattering (MEIS) showed that the concentration of N or the bonding or electronic state of N in the film was stable when the film was annealed at 950°C, while the oxygen (O) in HfSiON films was present in dissociated form, as evidenced by the unoccupied electronic state of O. The valence band offsets of the HfSiO films were strongly affected by N incorporation due to the presence of N in a 2p state. Moreover, a reduction in the conduction band offset of a HfSiO film was confirmed after the film was annealed in an atmosphere of N 2. The unoccupied state of the O vacancy is responsible for the change in the conduction band offset. The results of ab-initio calculations for the density of states (DOS) of HfSiO and HfSiON supercells were in agreement with the experimental results. The incorporation on N into HfSiO prevents the formation of a gap-state inside the band gap despite the fact that an O vacancy is generated in the film.
Bibliographical noteFunding Information:
This work was partially supported by the Joint Program for Samsung Electronics-Yonsei University and the IT R&D program of MKE/KEIT ( 10035320 , “Development of novel 3D stacked devices and core materials for the next generation flash memory”). We gratefully acknowledge the technical advice of K. Chae, C. C. Hwang, and H.-N. Hwang at PAL on beamline 7B1.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry