Al2O3 films are deposited using ion beam sputtering (IBS), ion beam reactive sputtering (IBRS), and electron beam evaporation (EBE). The properties of the films, such as optical identity, surface roughness, microstructures, and crystalline phase, are investigated. The single layer of alumina is discussed using the IBS method. It has a high refractive index and a perfect microstructure as well as a high ultraviolet (UV) absorption. The roughness of the Al2O3 film deposited using EBE is larger than that of the substrate surface, but it is in an acceptable range. The film deposited using EBE is dominated by the amorphous gamma phase, while the ones deposited using IBS and IBRS are an intermixture of the alpha alumina and the gamma alumina phases.