Dependence of blue-emitting property on nanopore geometrical structure in Al-based porous anodic alumina membranes

Porous anodic alumina (PAA) membranes were fabricated using anodization of Al foils. Based on morphology observations and photoluminescence (PL) measurements, it is revealed that the peak position of the observed blue PL band has an evident dependence on nanopore geometrical structure. The blue PL band is asymmetrical and can be Gaussian divided into two subbands, which originate in two kinds of oxygen-deficient centers, F+ and F centers. On raising the anodic voltage, the two subbands red shift and the intensity of the subband from the F+ centers relative to that from the F centers increases. This suggests that the increases of nanopore size and porosity make partial F+ stop centers convert into F centers. The mechanism of this conversion is further discussed on the basis of the PL behavior of the PAA membrane under ultraviolet irradiation. This work will be beneficial to the better understanding of the PL property of the PAA membrane.