Helicons and Nonresonant Cyclotron Absorption in Semiconductors. II.Hg1−xCdxTe

We have used microwave helicons of 23 and 70 GHz and nonresonant cyclotron absorption to measure the carrier densities, effective masses, and mobilities of electrons in ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$ for $0.135\le x\le 0.203$. Most measurements were made at 77°K, but some values are reported for 1.3°K. Carrier concentrations at 77°K ranged from 8×${10}^{20}$ to 2×${10}^{22}$ ${\mathrm{m}}^{-3\mathrm{}}$ and were sufficiently low to enable us to measure $m^{*}$ close to the conduction-band edge. The mass values, in the range $0.004m_0-0.010\mathrm{}{m}_0$, are in good agreement with values calculated from Kane's expression for the conduction band using literature values for the energy gap, its variation with temperature and alloy concentration, and the momentum matrix element, $P$. One specimen with $x=0.149\mathrm{}$ was studied from 77 to 185°K. Over this range the mobility was closely proportional to $T^{-2\mathrm{}}$. The variation of electron density permitted an estimate of the effective mass of the holes, ${m_h}^{*}=0.71\mathrm{}{m}_0$.