Compared to the p–n junction type device (Device A) with an n-type ZnO nanowire (n-ZnO)/p-type silicon (p-Si) hybrid structure, the newly designed device (Device B) with an n-ZnO/reduced graphene oxide sheet (rGO)/p-Si hybrid structure displays interesting electrical characteristics such as lower turn-on voltage and better current symmetry. The addition of rGO between n-ZnO and the p-Si substrate enables tuning of the p–n junctions into back-to-back Schottky junctions and lowering of the turn-on voltages, implying great potential applications in electronic and optoelectronic devices. The electrical characteristics and operating mechanism of these two devices are fully discussed.