Dielectric properties of capacitor materials in the optical frequency range

The optical properties and band gaps of capacitor materials are important for a number of reasons, including assessing the viability of candidate materials for gate dielectrics in semiconductors, identifying the electronic components of the polarizability, and monitoring degradation processes. This paper reports the high frequency dielectric function of several capacitor materials in the near UV to near IR range as determined by spectroscopic ellipsometry. Spectroscopic ellipsometry was also be used to determine changes in the depth profile due to changes in the dielectric function. In this work dielectric materials, primarily strontium titanate, were examined to determine their changes during DC electric field induced degradation.