Laser damage mechanism of porous Al2O3 films prepared by a two-step anodization method

Pure aluminum films were deposited on a B270 glass by electron beam evaporation technique. These aluminum films, which were used as anode, were put in sulfuric acid and oxalic acid to prepare porous alumina films using a two-step anodization method. The microstructure and laser damage characteristics of the alumina films were then tested. Results show that the microstructure of the alumina films formed in sulfuric acid and oxalic acid were vertical (cylindrical) pores with different diameters. The laser-damaged spot of the porous films was formed by innumerable small damaged pits with no mutual influence. Films prepared in different acids reveal different damage characteristics and reflect different mechanisms.