TITLE:
On the Conduction Mechanism of Silicate Glass Doped by Oxide Compounds of Ruthenium (Thick Film Resistors). 3. The Minimum of Temperature Dependence of Resistivity
AUTHORS:
Gulmurza Abdurakhmanov
KEYWORDS:
Lead-Silicate Glass, Thick Film Resistors, Minimum of Resistivity, Doping, Energy Bands, Conductivity, Thermal Activation, Hopping
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.4 No.3,
August
29,
2014
ABSTRACT: This article is the final part of the
investigation of conduction mechanism of silicate glass doped by oxide
compounds of ruthenium (thick film resistors). In the first part [1], the formation of percolation levels due to diffusion
of dopant atoms into the glass has been considered. The diffusion mechanism
allowed us to explain shifting of the percolation threshold towards to lower
value and the effect of firing conditions as well as the components composition
on the electrical conduction of the doped glass. The coexistence of thermal
activation and localization of free charge carriers as the result of
nanocrystalline structure of the glass was the subject of the second part [2]. Because of it, the
resistivity of the doped silicate glass is proportional to exp (–aT–ζ) at low temperatures (T 50 K), 0.4 ζ T > 800
K) and the conductivity of the doped silicate glass decreases sharply. We
consider the origin of the minimum in the temperature dependence of resistivity
of the doped silicate glass here. It is shown that the minimum arises from
merge of impurity band into the valence band of glass at temperature high
enough, so thermal activation of charge carriers as well as its hopping are
failed, and scattering of free charge carriers become predominant factor in the
temperature dependence of the resistivity.