A semiconductor device including a heterostructure having at least one low-resistivity p-type GaSb quantum well is provided. The heterostructure includes a layer of In0.52Al0.48As on an InP substrate, where the In0.52Al0.48As is lattice matched to InP, followed by an AlAsxSb1-x buffer layer on the In0.52Al0.48As layer, an AlAsxSb1-x spacer layer on the AlAsxSb1-x buffer layer, a GaSb quantum well layer on the AlAsxSb1-x spacer layer, an AlAsxSb1-x barrier layer on the GaSb quantum well layer, an In0.2Al0.8Sb etch-stop layer on the AlAsxSb1-x barrier layer, and an InAs cap. The semiconductor device is suitable for use in low-power electronic devices such as field-effect transistors.