Improving the degree of crystallinity of magnetron-sputtered Ta3N5 thin films by augmenting the ion flux onto the substrate

Ta3N5 is a promising candidate for a variety of applications, most notably as a photoactive material for solar water splitting. It is typically synthesized in a two-step process in which oxidized tantalum is annealed in NH3. Magnetron sputtering is an alternative synthesis method that is little explored to date, as first tries resulted in a small degree of crystallinity of the samples. In this paper, we report on the addition of an axial magnetic field to the conventional magnetron configuration which guides ionic species from the negative glow onto the growing film of Ta3N5. This ion-assisted growth is shown to result in a high degree of crystallinity, i.e. amorphous content, which is typical for conventionally sputtered films, is largely suppressed. The surface of such prepared films is nanostructured by a dense population of grains.