Replication Data for: Long-term protection of crystalline zinc phosphide under atmospheric conditions

Earth-abundant zinc phosphide (Zn3P2) holds great promise as a photovoltaic
absorber for thin-film applications, owing to its direct bandgap of approximately
1.5 eV and its high absorption coefficient in the visible spectrum.
Nonetheless, questions remain about the material’s stability in atmospheric
environments, given its tendency to react with surrounding water vapor and
oxygen. This work presents a comprehensive long-term study to understand
how environmental exposure impacts high-quality, monocrystalline epitaxial
zinc phosphide. Through a combination of various experimental techniques,
such as ellipsometry, Raman spectroscopy, X-ray diffraction measurements,
scanning transmission electron microscopy, energy dispersive X-ray spectroscopy,
secondary ion mass spectroscopy, and X-ray photoelectron spectroscopy,
we reveal that exposure to atmosphere causes substantial oxidation
of the thin film surface, penetrating several tens of nanometers into the bulk
material. Finally, we show that degradation can be effectively prevented by applying a thin dielectric layer, such as Si3N4 ,or simply by storing the unprotected
thin films under vacuum. These findings provide valuable guidelines
for the proper handling of the material prior to device fabrication.