Effective Electron Mass in CdTe

Measurements of the infrared Faraday effect and infrared reflectance of CdTe crystals are reported. Comparison of data on pure and on $n$-type doped crystals gave the free-carrier contributions to the Faraday rotation and to the dielectric constant, which, in turn, yielded the electron effective mass and carrier concentration in the doped crystals. The electron effective-mass ratio was found to be $\frac{m^{*}}{m}=0.11\mathrm{}\pm 0.01$, independent of the carrier concentration up to $N=1.7\mathrm{}\times {10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$. Comparison of the optically measured carrier concentrations with Hall effect data on the same samples determined the Hall scattering constant, $r$, which changed from 1.5 to 1.2 in the transition from nearly classical to nearly degenerate electron statistics.