Reduction of charge-center scattering rate inHg1−xFexSe

Abstract

The electrical resistivity, electron concentration, and mobility of ${\mathrm{Hg}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Fe}}_{\mathrm{x}}$Se are reported for 4.2<T<300 K and for 0.0001<x<0.12. The data are interpreted within an electronic band-structure model that assumes the existence of resonant donors (due to the presence of Fe ions) whose ground-state energy coincides with the conduction-band continuum. The electron-concentration data enable determination of the donor energy as a function of the temperature and crystal composition. Unexpectedly high values of the low-temperature electron mobility for ∼0.0003≤x≤0.01 indicate a reduction of the charged-impurity scattering rate at these temperatures. This effect is interpreted in terms of a spatial ordering of charges within the Fe-related impurity system.