Air-based sputtering deposition of titanium oxynitride-based single, gradient, and multi-layer thin films for photoelectrochemical applications

Titanium oxynitride (TiNxOy) thin films exhibiting tunable physical and chemical properties can be used in many fields. Air-based sputtering deposition of the films with diverse O/N ratios was employed to produce gradient and multilayer films. By solely altering the air/Ar flow ratio, obtained TiNxOy films could change from a crystalline to a mainly amorphous feature. Moreover, the carrier concentration, Hall mobility, and hence resistivity of the films could be modified to a large range. The optical bandgaps of the films could also be tailored to a wide extent. Based on these results, the gradient TiNxOy layer and TiNxOy/TiN(O) multilayer were also deposited on TiN(O)-coated glass substrates for the assessment of photoelectrochemical performance. Compared with the TiNxOy/TiN (O) bilayer with the best photoelectrochemical performance, the photoelectrochemical currents of gradient TiNxOy films could be improved from 99 +/- 2 mu A center dot cm- 2 to 164 +/- 2 mu A center dot cm- 2 by taking advantage of bandgap engineering. Additionally, the photoelectrochemical currents of TiNxOy/TiN(O) multilayer were further improved to 175 +/- 6 mu A center dot cm- 2. This is mainly due to conductive nano TiN(O) layers providing multiple high -transport paths while allowing light transmission. The enhancement mechanisms of the gradient and multi -layer films have also been elaborated.

Automated summary

This article discusses the use of titanium oxynitride (TiNxOy) thin films with tunable physical and chemical properties in various fields. By adjusting the air/argon flow ratio, the films can exhibit different crystalline or amorphous features, as well as varying carrier concentration, Hall mobility, resistivity, and optical bandgaps. These findings have implications for photoelectrochemical performance assessment.