Specific Heats of Cu, GaAs, GaSb, InAs, and InSb from 1 to 30°K

Abstract

The specific heats of Cu, GaAs, GaSb, InAs, and InSb have been measured over the temperature range from 1 to 30\ifmmode^\circ\else\textdegree\fi{}K with an accuracy of 0.5%. A comparison of the copper data with other published data verifies this estimate of the accuracy. The analysis of all four III-V compounds requires the inclusion of a free-carrier term linear in the temperature ($\frac{{c}_{\mathrm{fc}}}{T}\ensuremath{\sim}5$ \ensuremath{\mu}J/${\mathrm{K}}^{2}$ g at.) to explain the low-temperature data. The inclusion of this term results in excellent agreement between calorimetric and elastic-constant values of ${\ensuremath{\Theta}}_{0}$. A reduced plot of $\frac{\ensuremath{\Theta}}{{\ensuremath{\Theta}}_{0}}$ versus $\frac{T}{{\ensuremath{\Theta}}_{0}}$ shows a minimum (0.7 at approximately $\frac{T}{{\ensuremath{\Theta}}_{0}}=0.05$ which varies with average mass in both depth and location. The reduced $\frac{\ensuremath{\Theta}}{{\ensuremath{\Theta}}_{0}}$ curves for Ge and Si show qualitatively the same relative mass dependence but do not fall quantitatively into the pattern established by the compounds. The curve for GaAs (${\ensuremath{\Theta}}_{0}=347\ifmmode^\circ\else\textdegree\fi{}$K, $\overline{M}=72.32$) coincides with that of Si (${\ensuremath{\Theta}}_{0}=645\ifmmode^\circ\else\textdegree\fi{}$K, $M=28.086$) instead of Ge (${\ensuremath{\Theta}}_{0}=374\ifmmode^\circ\else\textdegree\fi{}$K, $M=72.59$), as might be expected. These heat-capacity data are used to recalculate temperature-dependent Gr\"uneisen parameters from previous thermal-expansion data.