HfO2 film was successfully grown on the 4H-SiC surface by using pulsed laser deposition system. The thermal stability and band offsets at the interfaces of HfO2/SiC and the effect of nitrogen on the electronic structures and thermal stability of HfO2 film have been investigated by using X-ray photoemission spectroscopy (XPS). Nitridation of HfO2 leads to reduction of the band gap and band offsets, but the atomic nitrogen can passivate oxygen vacancies in the dielectrics during nitridation process and improve interface thermal stability. Post nitridation annealing is required to increase the band gap and band offsets of dielectric film. (C) 2010 Elsevier B.V. All rights reserved.