In2O3　(111)　single-crystalline　films　have　been　grown　on　sapphire　(0001)　substrate　by　RF　plasma-assisted　molecular　beam　epitaxy.　The　epitaxial　relationship　between　the　film　and　substrate　was　determined　by　in　situ　reflection　high-energy　electron　diffraction,　ex　situ　Xray　diffraction　and　transmission　electron　microscopy.　Optical　and　electrical　measurements　show　that　the　undoped　In2O3　films　are　highly　transparent　and　conductive.　Twin　crystals　were　observed　as　the　main　defects　in　the　film　by　high-resolution　electron　microscopy.　The　film　may　be　used　for　transparent　electrical　contact　in　optoelectronic　devices,　such　as　ZnO-based　ultraviolet　diodes　and　lasers.　(c)　2006　Elsevier　B.V.　All　rights　reserved.