Heteroepitaxial Growth of a Ta3N5 Thin Film with Clear Anisotropic Optical Properties

Ta3N3 is a promising semiconductor photocatalyst which can generate H-2 gas from water under visible light illumination. It is expected that Ta3N5 exhibits a strong anisotropy in its physical properties stemming from its highly anisotropic crystal structure. However, such anisotropic properties have not been verified experimentally due to the difficulty in synthesizing a large single crystal. Here, we report the synthesis of (010)-oriented Ta3N5 single-crystalline thin films by solid phase epitaxy on the (110) plane of perovskite LaAlO3 substrates. The obtained epitaxial thin films of Ta3N5 exhibited clear optical anisotropy (pleochroism) as predicted by previous first-principles calculations. The optical gap for E parallel to[100] polarization (similar to 2.12 eV) was smaller than that for E parallel to[100] polarization (similar to 2.27 eV).

Automated summary

Ta3N5 is a promising semiconductor photocatalyst that can generate hydrogen gas from water under visible light illumination. By synthesizing single-crystalline thin films using solid phase epitaxy, the material exhibited clear optical anisotropy as predicted by previous calculations. The optical gap for different polarization directions showed variation in values.