The quantum Hall effect in a wide p-Ge1−x Six/Ge/p-Ge1−x Six potential well

Abstract

Quantum magnetotransport is investigated in a series of selectively doped p-type (Ge1−xSix/Ge)×N multilayered structures with Ge layer widths from 100 to 250 A in fields up to 35 T at 1.5–4.2 K. The plots of the magnetic-field dependence of the longitudinal (ρxx) and Hall (ρxy) magnetoresistance, as well as the ratio between the oscillation periods in strong and weak fields, vary significantly in samples with wide Ge layers and (or) with a high density of the two-dimensional gas. These features can be attributed to the participation of an additional subband in carrier transport. It follows from calculations of the structure of the Ge valence band under the conditions of size quantization and quantization by a magnetic field (performed in the approximation of an infinite rectangular potential well) that the additional subband can be the second heavy-hole quantum-well subband. Estimates of its population correlate with the experimental manifestations of the participation of the additional subband in galvanomagnetic phenomena.