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 at constant k ∥ is investigated. Using this technique we have studied differently strained Si/Si 1-x Ge 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 o with respect to each other