Refereed Articles
Coulomb Glass Origin of Defect-Induced Dielectric Loss in Thin Film Oxides
  The dielectric loss in amorphous, thin-film oxide insulators produces a real part of the ac conductivity sigma[prime](omega) that scales as omegas with s~1. Conventional models explain this frequency dependence by hopping or tunneling of charge between neighboring defect sites. These models fail at low temperatures since they predict that sigma[prime] should vanish at T = 0. We observe that the ac conductivity of Ta2O5, ZnO, and SiO2 has a nonzero extrapolated value at T = 0. We propose that this behavior is consistent with the predictions of a Coulomb glass, an insulator with a random distribution of charged defects.  
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    Coulomb Glass Origin of Defect-Induced Dielectric Loss in Thin Film Oxides.  R. Fleming, C. Varma, D. Lang, C. Jones, M. Steigerwald, G. Kowach, Appl. Phys. Lett. 2001, 78, 4016.