We studied the properties of Irish single-crystal thin films sandwiched by Al0.1In0.9Sb layers (with 0.5% lattice mismatch between InSb and Al0.1In0.9Sb) grown by molecular beam epitaxy on a GaAs substrate. The electron mobility of these Irish thin films was significantly higher and the electron density was very small in thin regions of less than 0.5 mu m compared to InSb thin films directly grown on the GaAs substrate. These results mean that the Al0.1In0.9Sb layers almost eliminated the large lattice mismatch effect observed at the InSb/GaAs hetero-interface. The dependence of electron mobility and electron density on temperature is also discussed with respect to the Irish thickness and Sri doping. (c) 2007 Elsevier B.V. All rights reserved.