Structural and photoluminescence properties of thin alumina films on silicon, fabricated by electrochemistry

Alumina thin films on a silicon substrate were fabricated by anodisation of Aluminium films, deposited by electron gun evaporation, in different acid aqueous solutions. The thickness of the initial Al film was changed in the range of 50–500 nm and its composition was either pure aluminium or aluminium with 1% silicon. The structure and properties of the obtained alumina films were extensively investigated and they were found to depend strongly on the thickness and composition of the initial aluminium layer, as well as on the acid aqueous solution used. One important result obtained from the optical characterization of the alumina films was the very bright photoluminescence (PL), which also depended on the acid aqueous solution used and the alumina film thickness. The obtained results will be discussed in detail.