Wavelength dependent photoluminescence of anodic alumina membranes

Abstract

Strong photoluminescence bands range from 300 to 600 nm at room temperature have been observed in anodic alumina membranes (AAM). It was found that the photoluminescence (PL) intensity and peak position of AAM depend strongly on the excitation wavelength, and the PL intensity of AAM prepared in C2H2O4 is much higher than for AAM prepared in H2SO4. There are two peaks in the PL bands; one is at constant wavelength of 460 nm, and the other increases almost linearly from 420 to 465 nm with excitation wavelength for AAM prepared in C2H2O4 and from 360 to 465 nm for AAM prepared in H2SO4. Annealing treatment of the as-prepared AAM results in an apparent reduction of the intensity of the blue emission at shorter excitation wavelength, while at longer excitation wavelength (longer than 320 nm) the PL intensity firstly increases, and at 500 ◦C reaches a maximum value, then decreases. It is considered that there are two PL centres; one originates from the oxygen-related defects in the barrier layer, and the other is correlated with the aluminum incorporated into the anion-contaminated alumina layer in the AAM. 1.