Pressure Dependence of the Carrier Concentrations inp-Type Alloys ofHg1−xCdxTeat 4.2 and 77°K

Electrical transport measurements have been made on $p$-type samples of ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$ with $x$ near 0.15 at temperatures of 4.2 and 77 °K and at hydrostatic pressures up to 9 kbar. A sharp transition is observed in both the Hall coefficient and conductivity versus pressure at 4.2 °K. The pressure dependence of the carrier concentrations and mobilities has been obtained from magneto-Hall and magnetoresistance data. Analysis using $\overrightarrow{\mathrm{k}}·\overrightarrow{\mathrm{p}}$ theory yields values for the Fermi energy, measured with respect to the valence-band edge, of more than 9 me V, which are independent of pressure. A possible model to account for this behavior is described. Magnetic freeze-out effects have been observed and attributed to the lowest-energy, spin-split, zero-order Landau level passing through the Fermi energy. A value of 7 × ${10}^{-6\mathrm{}}$ eV/bar is obtained for the pressure coefficient of the energy gap at 77°K. Non-Ohmic behavior has been observed at 4.2 °K during the magnetic freeze-out.