Sandwich-structure Al2O3/HfO2/Al2O3 gate dielectric films were grown on ultra-thin silicon-on-insulator (Sol) substrates by vacuum electron beam evaporation (EB-PVD) method. AFM and TEM observations showed that the films remained amorphous even after post-annealing treatment at 950 degrees C with smooth surface and clean silicon interface. EDX- and XPS-analysis results revealed no silicate or silicide at the silicon interface. The equivalent oxide thickness was 3 nm and the dielectric constant was around 7.2, as determined by electrical measurements. A fixed charge density of 3 x 10(10) cm(-2) and a leakage current of 5 x 10(-7) A/cm(2) at 2 V gate bias were achieved for Au/gate stack /Si/SiO2/Si/Au MIS capacitors. Post-annealing treatment was found to effectively reduce trap density, but increase in annealing temperature did not made any significant difference in the electrical performance. (c) 2005 Elsevier B.V. All rights reserved.