The quantum Hall effect in a wide p-Ge1-xSix/Ge/p-Ge1-xSix potential well

Quantum magnetotransport is investigated in a series of selectively doped p-type (Ge1-xSix/Ge) x N multilayered structures with Ge layer widths from 100 to 250 Angstrom in fields up to 35 T at 1.5-4.2 K. The plots of magnetic-field dependence of the longitudinal (rho(xx)) and Hall (rho(xy)) magnetoresistance, as well as the ratio between the oscillation periods in strong and weak fields, vary significantly in samples with Ge layers and (or) with a high density of the two-dimensional gas. These features can be attributed to the participation odf 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. (C) 1998 American Institute of Physics.