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

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 ($E_{X_1}-E_{{\Gamma }_1}$) of 0.315±0.015 eV at zero pressure and a mobility ratio of $\frac{{\mu }_X}{{\mu }_{\Gamma }}$ of $\frac{1}{32}$. The mobility ratio seems reasonable in comparison with $n$-GaAs.