Magnetic-field-induced localization in narrow-gap semiconductors Hg1-xCdxTe and InSb

Magnetotransport measurements on n-type Hg1-xCdxTe (x0.2) and InSb and far-infrared magnetooptical spectroscopy in Hg1-xCdxTe are reported. The transport data at magnetic fields below and near the magnetic-field-induced metal-insulator (M-I) transition indicate clear similarity of Hg1-xCdxTe and InSb. At fields well above the M-I transition and at low temperatures, the magnetotransport coefficients for Hg1-xCdxTe show anomalously weak dependences on field and temperature. This is attributed to shorting of the bulk by a conducting surface layer. Below the M-I transition field, an anomalous Hall effect is observed in both Hg1-xCdxTe and InSb. We interpret this effect within a model in which the M-I transition takes place in the donor impurity band. The impurity cyclotron resonance observed in Hg1-xCdxTe provides conclusive evidence for donor-bound electrons in this semiconductor and further confirms its similarity to InSb. The cyclotron-resonance data are in agreement with theoretical predictions for hydrogenic donors in a strong magnetic field. These observations provide strong evidence against the Wigner crystallization of electrons in Hg1-xCdxTe.