Probing band structure anisotropy in quantum wells via magnetotunneling

The resonances of a resonant tunneling structure are probed by a magnetic field applied parallel to the interfaces, which enables us to investigate the local band structure in k space. By rotating the magnetic field in the plane of the interfaces, the energy surface at constant ${\mathit{k}}_{\mathrm{\parallel }}$ is investigated. Using this technique we have studied differently strained Si/${\mathrm{Si}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ge}}_{\mathit{x}}$ quantum wells; we see a large anisotropy of the energy levels, with the symmetry axes of light holes and heavy holes being rotated 45° with respect to each other.