ELECTROLUMINESCENCE OF TB3-DOPED ANODIC TA2O5 FILMS()

The electroluminescence (EL) of Tb3+-doped anodic Ta2O5 films in the p resence of H2O2 was studied. Since the EL of the dopant Tb3+ ion shows the same potential (U) dependence as the background EL, light emissio n from Tb3+ can be used to monitor electrochemical processes at the ox ide/solution interface. In the rising part of the (EL,U) curve, both t he hole injection rate and the radiative recombination efficiency incr ease. This gives rise to a quadratic dependence of the intensity on th e current. The EL is not influenced by the rotation rate; ring-disk ex periments show the hole injection current to be kinetically limited. A t more negative potential, quenching of the emission occurs. Compariso n of the photoluminescence (PL) and EL intensities and spectra, which depend on the surroundings of the Tb3+ ion, indicates that the quenchi ng must be due to incorporation of hydrogen from the oxide/solution in terface. The anodic dark current resulting from cathodic polarization can be used as a measure of the concentration of the H-induced recombi nation centers.