Synthesis and electrical properties of ZnO nanowires

Vertically aligned ZnO nanowires were synthesized on the p+ silicon chip by modifying the CVD process with a vapor trapping design. Scanning electron microscopy was used to investigate the morphology of as-obtained nanowires. X-ray diffraction showed that the obtained nanowires were ZnO crystalline. The rectifying characteristics of the p–n heterojunction composed of ZnO nanowires and a p+ silicon chip were observed. The positive turn-on voltage was 0.5 V and the reverse saturation current was 0.01 mA. These vertically aligned ZnO nanowires showed a low field emission threshold of 4 V/μm at a current density of 0.1 μA/cm2. The dependence of emission current density on the electric field followed Fowler–Nordheim relationship.