Quantum confinement effects in Si/Ge heterostructures with spatially ordered arrays of self-assembled quantum dots

Magnetotunneling spectroscopy was employed to probe the confinement in vertical Si/Ge double-barrier resonant tunneling diodes with regularly distributed Ge quantum dots. Their current-voltage characteristics reveal a steplike behavior in the vicinity of zero bias, indicating resonant tunneling of heavy-holes via three-dimensionally confined unoccupied hole states in Ge quantum dots. Assuming parabolic confinement, we extract the strength of the confinement potential of quantum dots.