Dielectric permittivity of SiO[sub 2] thin films in dependence on the ambient hydrogen pressure.

Metal-silicondioxide-silicon structures with palladium electrodes, instead of standard gold or aluminum electrodes, show an increasing dielectric permittivity of the SiO[sub 2] films with increasing ambient hydrogen pressure. Measurements of the complex dielectric permittivity ε[sub SiO[sub 2]](f) in dependence on the hydrogen pressure are carried out at room temperature. The broad relaxational response spectra of the thin films result from a volume polarization effect. Correspondingly, the contribution of absorbed hydrogen to the dielectric permittivity is modeled by proton fluctuations in coulombic double-well potentials between pairs of oxygen ions. The broad distribution of relaxation times can be attributed to the distribution of interatomic distances between the oxygens within the amorphous SiO[sub 2]. From the experimental dielectric response spectra, a pair distribution function (PDF) of oxygens is derived. This PDF is similar to PDFs from literature, which originate from theoretical lattice simulations of amorphous SiO[sub 2]. As a quantitative result, we estimate the number of relaxation centers, i.e., oxygen pairs occupied by a proton, which contribute to the dielectric permittivity of the SiO[sub 2] thin films in dependence on the hydrogen pressure. [ABSTRACT FROM AUTHOR]