Weak localization in InSb thin films heavily doped with lead

Abstract

We study the weak localization (WL) in three-dimensional polycrystalline thin films of InSb. The films are closely compensated showing the electron concentration $n>{10}^{16} {\mathrm{cm}}^{\ensuremath{-}3}$ at the total concentration of the donor- and acceptor-type structural defects ${N}_{t}>{10}^{18} {\mathrm{cm}}^{\ensuremath{-}3}.$ Unless Pb doped, the InSb films do not show any measurable or show very small WL effect at 4.2 K. The Pb doping to the concentration of the order of ${10}^{18} {\mathrm{cm}}^{\ensuremath{-}3}$ leads to pronounced WL effects below 7 K. From the comparison of the experimental data on temperature dependence of the magnetoresistivity and sample resistance with the WL theory, the dependence of the phase destroying time ${\ensuremath{\tau}}_{\ensuremath{\varphi}}(T)$ is determined. It is concluded that the dephasing is connected to three separate processes. The first is due to the spin-orbit scatterings and is characterized by temperature-independent relaxation time ${\ensuremath{\tau}}_{\mathrm{so}}\ensuremath{\simeq}{10}^{\ensuremath{-}12} \mathrm{s}.$ The second is associated with the electron-phonon interaction $({\ensuremath{\tau}}_{i}\ensuremath{\sim}{T}^{\ensuremath{-}3}).$ The third dephasing process is characterized by temperature-independent relaxation time ${\ensuremath{\tau}}_{c}=(1--7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12} \mathrm{s},$ which is tentatively ascribed to inelastic scattering at extended structural defects. The resulting time ${\ensuremath{\tau}}_{\ensuremath{\varphi}}$ shows saturation in its temperature dependence for $\stackrel{\ensuremath{\rightarrow}}{T}0.$ The temperature dependence of the resistance can be explained by the electron-electron interaction for $T<1 \mathrm{K},$ and by the WL effect for $T>2 \mathrm{K}.$