Electrical transport and energy-band structure in InAs

The Hall coefficient and electrical conductivity were measured as a function of temperature for six different $n$-type InAs samples with carrier concentrations in the range 2.7×${10}^{22}$ to 4.5×${10}^{22}$ ${\mathrm{m}}^{-3\mathrm{}}$ at room temperature. For two other samples with carrier concentrations of 1.5×${10}^{22}$ and 3.8×${10}^{22}$ ${\mathrm{m}}^{-3\mathrm{}}$, respectively, measurements of electrical conductivity and Hall coefficient were made as a function of hydrostatic pressure up to 1.2 GPa at room temperature. Theoretical calculations were made for a three-band model including the ${\Gamma }_{1c}$ and two hole bands, and using various scattering mechanisms. The resulting values were fitted to the experimental data by using as adjustable such parameters as the high-frequency dielectric constant ${\kappa }_{\infty }$, the acoustic deformation potentials $E_{D\Gamma }$ and $E_{\mathrm{DH}}$ of the ${\Gamma }_{1c}$ and heavy-hole bands, respectively, and the pressure coefficient of the energy gap ${\alpha }_p$. The resulting analysis indicates that polar optical scattering is dominant in the ${\Gamma }_{1c}$ band while scattering due to nonpolar optical phonons is most important in the heavy-hole band. Below ∼100°C, the transport properties can be explained in terms of the ${\Gamma }_{1c}$ band only. The effect of the light holes turns out to be negligible in the present work in a temperature range from room to 270°C, while heavy holes become important at above ∼100°C because of intrinsic activation into the ${\Gamma }_{1c}$ band. The heavy holes thus provide scattering centers for the electrons, although their direct contribution to charge transport remains very small. The final fitting was obtained with the following values, ${\kappa }_{\infty }=12.37\mathrm{}$, ${\alpha }_p=0.114\mathrm{}$ eV/GPa, $E_{D\Gamma }=13.6\mathrm{}$ eV, and $E_{\mathrm{DH}}=4.0\mathrm{}$ eV.