Light emission from silicon-based porous anodic alumina formed in 0.5 M oxalic acid

We have examined the photoluminescence (PL) spectra of silicon-based porous anodic alumina formed in 0.5 M oxalic acid. A broad PL band centered at 565 nm was observed. Spectral analyses reveal that the broad PL arises from optical transitions between the energy levels of F-2(+) center (a combined oxygen vacancy with one positive charge). In addition, two ultraviolet and one violet PL band, together with a blue band, were also obtained from this kind of Si-based porous anodic alumina. Based on annealing behavior of these PL bands, we suggest that the ultraviolet and violet PL bands are closely related to excess aluminum ions in the alumina membrane rather than oxygen vacancy defects reported previously. The blue emission originates in oxygen vacancies (F and F+ centers). This work provides a good understanding of the light-emitting properties of silicon-based porous anodic alumina templates. (C) 2003 American Institute of Physics.