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 X₁ 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_X1-E_Γ1) of 0.315±0.015 eV at zero pressure and a mobility ratio of μ_X/μ_Γ of 1/32. The mobility ratio seems reasonable in comparison with n-GaAs.