Composition-dependent energy spectrum of electrons in Hg1-xFexSe solid solution.

Abstract

The composition dependence of the electron energy spectrum in the ${\mathrm{Hg}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Fe}}_{\mathit{x}}$Se solid solution investigated assuming the invariability of the position of the Fe d resonant level in the absolute energy scale. In the linear-in-x approximation, the individual shifts of the extrema of the ${\mathrm{\ensuremath{\Gamma}}}_{6}$ and ${\mathrm{\ensuremath{\Gamma}}}_{8}$ bands are determined from analysis of the x-dependent concentration of the conduction electrons n as ${\mathit{dE}}_{\mathrm{\ensuremath{\Gamma}}6}$/dx=2.10\ifmmode\pm\else\textpm\fi{}0.05 eV and ${\mathit{dE}}_{\mathrm{\ensuremath{\Gamma}}8}$/dx=-2.45\ifmmode\pm\else\textpm\fi{}0.05 eV. It is shown that a quantitative description of the experimentally observed n(x) and \ensuremath{\mu}(x) dependences (where \ensuremath{\mu} is the mobility of the conduction electrons) is achieved when taking into account changes of only two parameters of the theory corresponding to the positions of the extrema of the ${\mathrm{\ensuremath{\Gamma}}}_{6}$ and ${\mathrm{\ensuremath{\Gamma}}}_{8}$ bands. The energy of the conduction-band bottom is found to vary in a wide range (\ensuremath{\sim}100--330 meV) with respect to the iron level. This explains, in particular, the absence of saturation of the contribution from scattering by ionized donors to \ensuremath{\mu}(x), calculated in terms of the short-range correlation model. The transition from the semimetal to the semiconductor state is found to be at x\ensuremath{\approxeq}0.06.