Weak antilocalization and low-temperature characterization of sputtered polycrystalline bismuth selenide

Abstract

We report a thorough crystal and transport characterization of sputtered polycrystalline BixSe1−x (20 nm), grown on a thermally oxidized silicon substrate. The crystal and grain structures of the sample are characterized by transmission electron microscopy. Selected-area electron diffraction shows a highly polycrystalline structure. Transport measurements suggest semiconducting behavior of the BixSe1−x film with a very high carrier concentration (∼1020 cm3) and low mobility [∼8 cm2/(V s)]. High-field magnetoresistance measurements reveal weak antilocalization, to which both the low mobility and the angular dependence suggest an impurity-dominated contribution. Fitting parameters are obtained from 2D magnetoconductivity using the Hikami-Larkin-Nagaoka equation. The variation of the phase coherence length with temperature suggests electron–electron scattering for phase decoherence. Electron–electron interaction theory is used to analyze the low-temperature conductivity.