Mobility of Charge Carriers in Semiconducting Layer Structures

Abstract

The electrical resistivities and the Hall constants of the compound semiconductors GaSe, Mo${\mathrm{S}}_{2}$, Mo${\mathrm{Se}}_{2}$, and W${\mathrm{Se}}_{2}$, which crystallize in layer structures, have been measured at temperatures ranging from 100 to 700\ifmmode^\circ\else\textdegree\fi{}K. The Hall mobilities derived from these measurements are all of the order of 100 ${\mathrm{cm}}^{2}$/V sec at room temperature, and they exhibit a temperature dependence of the form $\ensuremath{\mu}\ensuremath{\propto}{(\frac{T}{{T}_{0}})}^{\ensuremath{-}n}$, where $n=2.1$ for GaSe, $n=2.6$ for Mo${\mathrm{S}}_{2}$, and $n=2.4$ for Mo${\mathrm{Se}}_{2}$ and W${\mathrm{Se}}_{2}$. A short-range interaction is discussed which couples the charge carriers in highly anisotropic layer structures to the nonpolar optical lattice modes. The relatively low room-temperature mobilities as well as the high values of the exponents $n$ are explained in terms of the proposed interaction.