Schematic of the Cu2O/PbS semiconductor heterojunction on Au (100) showing the epitaxial relations between the layers. The 0.5-μm-thick PbS and Cu2O films were consecutively electrodeposited onto a Au(100) single crystal at room temperature. Both layers showed a strong (100) out-of-plane texture. Azimuthal X-ray diffraction studies of the in-plane relationships revealed that the PbS structure is rotated 45° relative to the substrate, while the Cu2O overlayer shows no rotation with respect to Au.