Electron tunneling in a strained n-type Si_1-xGe_x/Si/Si_1-xGe_x double-barrier structure

We report electrical measurements on an n-type Si_1-xGe_x/Si/Si_1-xGe_x double-barrier structure grown on a partially relaxed Si_1-yGe_y buffer layer. Resonance tunneling of Δ₄ band electrons is demonstrated. This is attributed to the strain splitting in the SiGe buffer layer where the Δ₄ band is lowest in energy at the electrode. Since the Δ₄ band electrons have a much lighter effective mass along the direction of tunneling current in comparison with that of the Δ₂ band electrons, this work presents an advantage over those SiGe resonant-tunneling diodes in which tunneling of Δ₂ band electrons is employed.