InAs-based two-dimensional electron systems grown on lattice mismatched InP substrates offer a robust platform for the pursuit of topologically protected quantum computing. We investigated strained composite quantum wells of In$_{ 0.75}$Ga$_{ 0.25}$As/InAs/In$_{ 0.75}$Ga$_{ 0.25}$As with In$_{ 0.75}$Al$_{ 0.25}$As barriers. By optimizing the widths of the In$_{ 0.75}$Ga$_{ 0.25}$As layers, the In$_{ 0.75}$Al$_{ 0.25}$As barrier, and the InAs quantum well we demonstrate mobility in excess of $1 \times 10^{ 6}\,$cm$^{ 2}/$Vs. Mobility vs. density data indicates that scattering is dominated by a residual three dimensional distribution of charged impurities. We extract the Rashba parameter and spin-orbit length as important material parameters for investigations involving Majorana zero modes.
Categories: cond-mat.mtrl-sci cond-mat.mes-hall