Conduction-Band Structure of GaSb from Pressure Experiments to 50 kbar

Abstract

The pressure variation of the resistivity of S-, Se-, and Te-doped ($n$-type) GaSb has been studied to 50 kbar. All three types exhibit a saturation in resistivity at the highest pressures attained, although the resistivity of S- and Se-doped samples increases several orders of magnitude before saturation, in contrast to Te-doped samples, whose resistivity increases only by a factor of 14. The saturation in resistivity is due to the ${X}_{1}$ minima becoming the lowest conduction-band edge at these pressures. Analysis of S- and Te-doped GaSb data, using a model of three different conduction-band minima (with the addition of one impurity level in the S-doped sample) and the known rate of motion of the bands, is consistent with an interband separation (${E}_{{X}_{1}}\ensuremath{-}{E}_{{\ensuremath{\Gamma}}_{1}}$) of 0.315\ifmmode\pm\else\textpm\fi{}0.015 eV at zero pressure and a mobility ratio of $\frac{{\ensuremath{\mu}}_{X}}{{\ensuremath{\mu}}_{\ensuremath{\Gamma}}}$ of $\frac{1}{32}$. The mobility ratio seems reasonable in comparison with $n$-GaAs.