Preparation of anodic Al2O3 films on SiO2 substrate and their photoluminescence properties

nm thick aluminum films were deposited on SiO_2 substrates by heat evaporat ion. At 0 ℃, 40 V DC voltage, the authors successfully prepared h igh density Al_2O_3 films by anodic oxidation on SiO_2 substrates with 15 wt% H_2SO_4 as electr olyte, and AFM was employed to study the film surface morphology. A t room temperatu re the authors measured the photoluminescence spectrum of Al_2O_3 films prep ared at dif ferent anodic voltages excited by Xe lamp. In addition, the authors monitore d their excit ation spectra of different emission peaks, and the authors found that the relati ve emiss ion intensity gets weaker and shifts to lower energy at higher anodic voltage. At 40 V anodic voltage the authors observed new 356 nm ultraviolet emission, w hich has the same 210 nm excitation emission. Based on the discussion of the relative intensi ty of the PL spectra of anodic alumina at different voltages, the authors sugges t that F and F+ oxygen vacancy defects were responsible for the observed 356 and 38 6 nm ultraviolet photoluminescence from Al_2O_3 anodic film at 40 V voltage.