Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300℃. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction （XRD）, high- resolution transmission electron microscopy （HRTEM）, and x-ray photoelectron spectroscopy （XPS）. The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3 nm and 0.Snm, respectively. XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.
