VALENCE-BAND LANDAU-LEVEL MIXING AND ANISOTROPY IN SI1-XGEX INVESTIGATED BY RESONANT MAGNETOTUNNELING

We report magnetotunneling measurements on strained p-Si/Si1-xGex doub le-barrier resonant tunneling structures in fields up to 30 T. In the I(V, B(parallel-to)) characteristics of the first heavy-hole peak we o bserve satellite resonances corresponding to tunneling with DELTAn = 1 and DELTAn = 2 changes in Landau index n. The relative intensity of t he satellite peaks excludes scattering as a possible mechanism and we attribute the DELTAn = 1, 2 peaks to elastic tunneling made possible b y Landau level mixing. The observed strong DELTAn = 2 mixing could ari se from the large E(k(perpendicular-to)) anisotropy in the Si1-xGex qu antum well, which we probe by I(V, B(perpendicular-to)) measurements. From the shifts in the heavy-hole peak with in-plane B(perpendicular-t o) orientation we find that at large k(perpendicular-to) the in-plane mass varies strongly between the [110] (heavy) and [100] (light) cryst allographic directions.