Resonant tunneling of holes in Si/SixGe1−xquantum-well structures

Resonant tunneling of holes in Si/${\mathrm{Si}}_{\mathit{x}}$ ${\mathrm{Ge}}_{1\mathrm{-}\mathit{x}}$ systems is investigated. From the comparison between theory and experiment, we find clear evidence for resonant tunneling of incoming heavy holes through light-hole states in the well. Measurements with magnetic fields applied parallel and perpendicular to the layers confirm this interpretation. With the magnetic field parallel to the current, Landau levels are observed in the derivatives of the tunneling characteristics. From the Landau-level spacing the in-plane effective mass in the well is extracted.