First-principles Calculations of the Dielectric Constant for the GeO2 Films

Dielectric properties of a-quartz and rutile-GeO2 thin-films are investigated using first-principles ground-state calculations in external electric fields. The optical and the static dielectric constants inside the films have nearly-constant values, corresponding to their bulk values, while only at the topmost surface layer the dielectric constants decrease distinctly. It has been found that the dielectric constant for the rutile-GeO2 is larger than that for the a-quartz one, which stems from the larger ionic character of the Ge-O bond for the rutile phase.