Transparent nanoscale-film heterojunctions based on Cu₂O and ZnO were fabricated by atomic layer deposition and reactive magnetron sputtering. The constitutive layers exhibit high crystalline quality and a local epitaxial relation between Cu₂O and ZnO was achieved with [110] Cu2O || [001] ZnO and [001] Cu₂O || [010] ZnO as evidenced by high resolution transmission electron microscopy and. Cu₂O films show very low resistivity and high mobility values of 9–150 Ω cm and 19 cm2/V s, respectively. The Cu₂O/ZnO heterojunctions exhibit a nonlinear rectifying behavior characteristic of a p–n junction, self-powered photoresponse under 1 Sun illumination and an average transmittance of 73% in the visible region of the electromagnetic spectrum. These results are promising for all-oxide transparent electronics, photodetection and photovoltaic applications.