Band alignment issues related to HfO2/SiO2/p-Si gate stacks
The valence and conduction band densities of states for the HfO2/SiO2/Si structure are determined by soft x-ray photoemission and inverse photoemission. First principles calculations are used to help in assigning valence band maxima and conduction band minima. The energies of defect states at the band edges are estimated by comparing the theoretical and experimental results. Determinations of the local surface potentials before and after a forming gas anneal are used to help determine the possible location of the charge in the film.