Resonant tunneling of variously strained Si/Ge_xSi_1-x/Si heterostructures

Resonant tunneling of holes through variously strained double barrier Si/Ge_xSi_1-x/Si structures grown on a relaxed GeSi buffer layer has been observed. The different GeSi buffer layer has a lattice constant determined by the Ge fractional composition and the strained double barrier tunneling structures are then grown by molecular beam epitaxy onto the relaxed buffer layer. Tunneling of light and heavy holes has been demonstrated. The current-voltage relations show negative differential resistance. The positions of the resonant peaks are in agreement with the light and heavy hole bound states in the quantum well calculated from the deformation potential and the strain data. The tunneling current is also measured in the presence of a high magnetic field up to 10 T, both in the perpendicular and parallel to the interfaces.