Characterization of Baddeleyite-structure NbON Films Deposited by RF Reactive Sputtering for Solar Hydrogen Production Devices

In this study, baddeleyite-structure NbON was investigated as new photocatalysts for solar hydrogen production devices. We deposited pure 90-nm-thick NbON films on quartz substrates under a fixed O2 and N2 ambient mixture by RF reactive sputtering. The NbON films showed semiconductive characteristics and a narrower band gap than that of TaON. The band gap of NbON was estimated to be 2.1 eV. We confirmed that the NbON film was very dense without distinct cracks and had an approximately stoichiometric and uniform composition. We prepared an NbON photoelectrode on a conducting substrate and clearly observed the photocurrent by 436-nm monochromatic light. NbON has potential as a photocatalyst for direct water splitting.