Electron weak localization, and electron–phonon interaction in amorphous zinc-doped indium oxide films

We have systematically investigated the temperature dependence of resistivity ρ and Hall coefficient RH of indium zinc oxide films with thickness d = 350 nm in the temperature range 2.0 K to 300 K. Specimen films with ρ ⋍ 3−17 μΩ m (300 K) show metallic characteristics (ρ ∝ T) at temperatures above 100 K. At low temperatures below 20 K, the resistivity slightly increases with decreasing temperature because of the quantum effects in disordered systems. By eliminating carefully quantum effects ρquanta and the residual resistivity ρ0, we have found that the resistivity changes in the form of ρ ∝ ρ0T2 at temperatures below ⋍ 100 K. This characteristic indicates the existence of resistivity ρel–ph–imp due to the interference effect between the impurity scattering and the electron–phonon scattering. It has been found that the temperature dependence of ρ(T)for all present films agrees well with the sum of the Bloch–Grüneisen term ρel–ph = βF(T,ΘD) and the interference term ρel–ph–imp = Bel–ph–impG(T,ΘD) in a temperature region 20 K to 300 K. From analyses, regarding the coefficients β, Bel–ph–imp, and the Debye temperature ΘD as fitting parameters, we obtain the ΘD ⋍ 970–1060 K and the longitudinal sound velocity vℓ ⋍ 14,000 m/s under some assumptions.