Properties of magnetotransport in three-dimensional quantum-dot structures

Magnetotransport through a three-dimensional quantum dot embedded in vertical quantum wires in the presence of parallel magnetic fields is investigated theoretically. The conductance spectra and the electron densities are calculated by the scattering-matrix method. It is found that the characteristics of the magnetoconductance depend strongly on the alignments between the quantum wires and the embedded quantum dot. When the central axes of different components are aligned, the conductance spectra are found to be characterized by antiresonance dips at low magnetic fields and only by plateaus at high magnetic fields. In contrast, when the central axes are misaligned, the conductance spectra are found to be characterized by a mixture of antiresonance dips and tunnelling peaks in the low-magnetic-field region and only by tunnelling peaks in the high-magnetic-field region. A simple but physically motivated model gives an analytical formula which not only compares well with but also provides a reasonable explanation for the numerical data. On the basis of these magnetotransport properties, a method for experimental determination of the alignment of different components in a vertical electronic device is proposed.