The Hall effect and electron energy spectrum near the conduction band edge of n-CdSb in magnetic fields up to 25 T

The Hall effect in the II-V group semiconductor n-CdSb doped with In is investigated in pulsed magnetic fields up to B = 25 T and temperatures between T = 2 and 77 K for samples oriented along the [ 0 1 0] and [ 0 0 1] crystallographic axes. The Hall coefficient, R (B, T), exhibits a sequence of an almost flat region followed by a descending interval and an upturn when B is increased. The decrease of R (B, T) is interpreted by the presence of two groups of electrons with concentrations n(2)(T)> n(1)(T) and mobilities mu(2)(T)<mu(1)(T). Analysis of n(1)(T) and n(2)(T) demonstrates that the high-mobility carriers n(1) are the conduction band (CB) electrons, whereas the low-mobility carriers n(2) are itinerant electrons of a lower resonant impurity band (IB), having at low T energies of E-i similar to 3-4 meV above the CB edge. In addition, near the CB edge lies a higher IB containing only localized electron states. The IBs are split by spin to states differing by an energy Delta E-i approximate to 0.9 meV. The upturn of R (B, T) in the high-field region is explained by the redistribution of the electrons between the IBs due to the decrease of Delta E-i when B is increased. The mobility of the CB electrons is determined presumably by strong anisotropic scattering on neutral impurity centres, accompanied at high T by isotropic scattering on acoustic phonons, whereas scattering from ionized impurities is small.