Photoelectrochemical evidence of inhomogeneous composition at nm length scale of anodic films on valve metals alloys
- Authors: Santamaria, M.; Di Franco, F.; Di Quarto, F.; Habazaki, H.; Zaffora, A.
- Publication year: 2015
- Type: Abstract in atti di convegno pubblicato in volume
- Key words: Photoelectrochemical characterization, nm length scale, anodic films, valve metals alloys
- OA Link: http://hdl.handle.net/10447/189671
Anodic films of different thickness (∼30 nm and 70 nm) were grown by anodizing sputtering-deposited Ta-19at% Al to different formation voltages. N incorporation into the anodic films was inducing by performing the anodizing process in ammonium containing solutions. Layered anodic films were prepared by a double formation procedure with a first anodizing step in ammonium biborate solution and second anodizing step in borate buffer solution, or vice versa. Glow Discharge Optical Emission Spectroscopy was employed to show the distribution of N across the oxide. Photoelectrochemical measurements evidenced a red shift of the light absorption threshold due to N incorporation. A model was proposed and tested to model the dependence of quantum yield on photon energy and, thus, to estimate the band gap of the layers for both anodized Ta and Ta-19at% Al.