In this study, the influence of the degree of crystallization and thickness of films was correlated with the photoelectrochemical performance of SrTaO2N semiconductor films for O2 evolution reaction under visible light irradiation. Oxynitride films were deposited on various substrates using the sputtering in Ar + N2 reactive atmosphere from a home-made SrTaO2N target. Films with stoichiometric composition were obtained at a high temperature (TS =800 °C) with reduced bandgap. The different substrates led to diverse degrees of film crystallization, from weakly crystallized to fully c-axis oriented. The photoelectrochemical performance was improved by improving the film crystallinity and the thickness. For further improvement of the photoelectrochemical performance, the following three limiting factors are identified: 1) low absorption coefficient, especially in the visible domain from 500 to 600 nm; 2) short lifetimes of excited charge carriers; and 3) permittivity with only moderate values lower than 10 in the visible-light domain.
|Journal of the European Ceramic Society
|Published - May 19 2020
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the European Union through the European Regional Development Fund (ERDF) and by the Ministry of Higher Education and Research, Brittany Région and Côtes d’Armor Département through the CPER Projects MATECOM and SOPHIE-STICC. This publication work was also supported by the Conseil Départemental des Côtes d’Armor, Saint Brieuc Armor Agglomération, and the Syndicat de Gestion du Pole Universitaire de Saint Brieuc (France). The authors thank Prof. Hicham Idriss and Dr. Habib Katsiev at SABIC corporation for providing the fs pump-probe spectrometer utilities and for the support in the measurements.