Thin films of Y2O3 were grown by molecular-beam epitaxy on silicon aiming at material with adequate crystal quality for use as high-κ gate replacements in future transistors. It was found that Y2O3 grows in single-crystalline form on 4° misoriented Si(001), due to an in-plane alignment of <110>Y2O2 to the silicon dimer direction. The Y2O3 layers exhibit a low degree of mosaicity, a small proportion of twinning and sharp interfaces. This represents a significant improvement compared to material grown on exact silicon surfaces. © 2002 American Institute of Physics.