Electron–Electron Interactions in Sb-Doped SnO2 Thin Films

Abstract

Electrical conductivity and Hall-effect measurements on undoped and Sb-doped SnO 2 thin films prepared by the sol-gel technique were carried out as a function of temperature (55 K to 300 K). Structural characterizations of the films were performed by atomic force microscopy (AFM) and x-ray diffraction (XRD). A doping-induced metal-insulator transition (MIT) was observed. On the metallic side of the transition, the experimental data were interpreted in terms of electron-electron interactions (EEI). The existence of EEI was confirmed by excellent agreement between theoretical and experimental data. The experimental data on the insulator side of the transition were analyzed in terms of variable-range hopping (VRH) conduction. A complete set of parameters describing the properties of the localized electrons, including hopping energy, hopping distance, and the value of the density of states at the Fermi level, was determined.

Electronic structure and transport measurements of amorphous transition-metal oxides: observation of Fermi glass behavior

“…Electron conduction in Fermi glasses takes place by hopping. In the variable-range hopping (VRH) regime, the electrons hop between neighbors nearest (NN) in space, R, or in energy, W , within the optimum bandwidth E F ± W [19,[29][30][31][32][33][34][35], and hence the conductivity is proportional to the hopping probability as…”

Improved conductivity of Sb-doped SnO2 thin films

“…12,13 In order to understand the effect of the films thickness on the EEI contribution in Sb-doped SnO 2 thin films, three films having different thickness have been investigated in this work apart from a previous one. 11 The films addressed here differ from those studied previously on effect of Sb doping for the electrical transport properties of SnO 2 . 11…”

“…This is consistent with observations reported on SnO 2 films which exhibit metallic impurity band conduction with a high carrier concentration and a low mobility. 11 Fig. 2 shows the measured electrical conductivity of the films with different thickness as a function of temperature (DT ¼ 55-155 K).…”

“…4 A currently accepted mechanism leading to the improvement of the conductivity was already presented in the literature. 11 The key point lies in the assumption of highly degenerate of the SnO 2 material. Therefore, the simple Boltzmann equation was improved according to the method proposed by various authors.…”

“…7,8 Doping with thorium, fluorine, antimony, etc., is an effective way to enhance the electrical conductivity of SnO 2 . [9][10][11] When doping level is high, the position of the Fermi energy (E F ) level lies within the conduction band (for n-type) and it causes to the formation of a degenerate band. In the case of highly degeneration, a system can exhibit a disordered metallic conductivity due to presence of various disorders in structure.…”