Methods and systems for determining band structure characteristics of high-k dielectric films deposited over a substrate based on spectral response data are presented. High throughput spectrometers are utilized to quickly measure semiconductor wafers early in the manufacturing process. Optical dispersion metrics are determined based on the spectral data. Band structure characteristics such as band gap, band edge, and defects are determined based on optical dispersion metric values. In some embodiments a band structure characteristic is determined by curve fitting and interpolation of dispersion metric values. In some other embodiments, band structure characteristics are determined by regression of a selected dispersion model. In some examples, band structure characteristics indicative of band broadening of high-k dielectric films are also determined. The electrical performance of finished wafers is estimated based on the band structure characteristics identified early in the manufacturing process.