Fabrication of transparent p–n heterojunction thin film diodes based entirely on oxide semiconductors

All oxide-based, transparent polycrystalline $\mathrm{p–n}$ heterojunctions on a glass substrate were fabricated. The structure of the diode was $n^{+}-\mathrm{ZnO}$ $\mathrm{electrode}\mathrm{/n-}\mathrm{ZnO}\mathrm{/p-}{\mathrm{SrCu}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{2}}{\mathrm{/In}}_{\text{2−x}}{\mathrm{Sn}}_x{\mathrm{O}}_{\mathrm{3}}$ electrode on the substrate. The contact between the n- and p-type semiconducting oxides was found to be rectifying. The ratio of forward current to the reverse current exceeded 80 within the range of applied voltages of −1.5 to +1.5 V and the estimated diode factor (n value) was 1.62. The diode structure was fabricated on a glass plate with the total thickness of 1.3 μm and possessed an optical transmission of 70%–80% in the visible region.