Band alignment at the strontium germanate interface with silicon

Photocatalytic water splitting is a promising strategy for large-scale clean energy production. However, efficient and low-cost solid-state photocatalysts are still lacking. We present here first-principles calculations for investigating the suitability of an epitaxial layer of strontium germanate on a Si(100) single crystal as a photocathode. Conduction and valence band offsets at the interface between these two semiconductors were determined using state-of-the-art approximations of density functional theory for the accurate prediction of band alignments. The resulting band lineup is also confirmed by inspection of the spatially resolved density of states. It is concluded that the conduction band offset of the investigated heterostructure is favorable for photocathodic functionality.