Valence band Landau level mixing and anisotropy in Si_1-xGe_x investigated by resonant magnetotunneling

Abstract

We report magnetotunneling measurements on strained p- Si Si1-Gex double-barrier resonant tunneling structures in fields up to 30 T. In the I(V,B∥) characteristics of the first heavy-hole peak we observe satellite resonances corresponding to tunneling with Δn = 1 and Δn = 2 changes in Landau index n. The relative intensity of the satellite peaks excludes scattering as a possible mechanism and we attribute the Δn = 1, 2 peaks to elastic tunneling made possible by Landau level mixing. The observed strong Δn = 2 mixing could arise from the large E(k⊥) anisotropy in the Si1-xGex quantum well, which we probe by I(V, B⊥) measurements. From the shif heavy-hole peak with in-plane B⊥ orientation we find that at large k⊥ the in-plane mass varies strongly between the 〈110〉 (heavy) and 〈100〉 (light) crystallographic directions. © 1994.