Transparent yttrium hydride thin films prepared by reactive sputtering

Metal hydrides have earlier been suggested for utilization in solar cells. With this as a motivation we have prepared thin films of yttrium hydride by reactive magnetron sputter deposition. The resulting films are metallic for low partial pressure of hydrogen during the deposition, and black or yellow-transparent for higher partial pressure of hydrogen. Both metallic and semiconducting transparent YHx films have been prepared directly in situ without the need of capping layers and post-deposition hydrogenation. Optically the films are similar to what is found for YHx films prepared by other techniques, but the crystal structure of the transparent films differ from the well-known YH3−η phase, as they have an fcc lattice instead of hcp.

Research highlights▶ Thin films of transparent (semiconducting) and black (metallic) yttrium hydride. ▶ Magnetron sputtering with an yttrium target and hydrogen as a reactive gas. ▶ Optical transmission and reflection resemble β-YH2 (black) and γ-YH3 (transparent). ▶ XRD shows that transparent films have an expanded fcc lattice with a = 5.35 Å. ▶ Samples are stable at ambient conditions.