Local Dielectric Property of Cubic, Tetragonal, and Monoclinic Hafnium Oxides

We investigate the electronic contribution to local dielectric property in terms of the local polarizability density and dielectric constant density, for the cubic, tetragonal, and monoclinic structure of HfO2 and compare their dielectric properties with those of SiO2. We show appropriate termination conditions of our cluster models to realize the condensed property of dielectric; point charge conditions for HfO2 whose bond is ionic, while hydrogen termination conditions for SiO2 whose bond has covalent property. We show that local parts of materials have complicated responses to external electric fields, in particular, rotational ones. Hence, nanosize materials should be studied in the local and tensor quantity analysis to describe rotational responses correctly. It is clarified that the electronic contribution to local polarizability and dielectric constant densities is almost independent of the structures of HfO2 crystals. We show that the electronic contribution to dielectric response of HfO2 is significantly large compared to those of SiO2. In addition, it is found that the average value of dielectric constant around O atoms is larger than other regions in both HfO2 and SiO2. (C) 2012 The Japan Society of Applied Physics