InSb/Al${}_x$In${}_{1-x}$Sb heterostructures display intrinsic parallel conduction in the buffer layer at room temperature that limits exploitation of the high-mobility two-dimensional electron gas (2DEG), particularly for nanostructured devices where deep isolation etch processing is impractical. Here, we demonstrate a strategy to reduce the parasitic conduction by the insertion of a pseudomorphic barrier layer of wide-band-gap alloy below the QW. We have studied the high-field magnetotransport in two types of InSb/Al${}_x$In${}_{1-x}$Sb modulation doped quantum well heterostructures with and without the barrier layer in the temperature range 2–290 K and magnetic fields to 7.5 T. The conduction in the doping layer, the 2DEG, and the buffer layer are analyzed using a multi-carrier model that successfully captures the field dependence of the Hall resistance over the experimental field range. Samples with the barrier layer show significantly reduced buffer layer conduction compared to samples without. Our results are expected to be of importance for ambient temperature nano-electronic operation.

• Received 25 May 2011

DOI:https://doi.org/10.1103/PhysRevB.84.075474