Investigation of electrical and ammonia sensing characteristics of Schottky barrier diode based on a single ultra-long ZnO nanorod

Novel ultra-long ZnO nanorods, with lengths about 0.5-1.5 mm and diameters ranging from 100 to 1000 nm, in mass production have been synthesized via the vapor-phase transport method with CuO catalyst at 900 °C. Rectifying Schottky barrier diodes have been fabricated by aligning a single ultra-long ZnO nanorod across paired Ag electrodes. The resulting current-voltage (I-V) characteristics of the SBD exhibit a clear rectifying behavior. The ideality factor of the diode is about 4.6, and the threshold voltage is about 0.54 V at room temperature (300 K). At the same time the detailed I-V characteristics have been investigated in the temperature range 423-523 K. In addition, after exposure of the Schottky diodes to NH₃, the forward and reverse currents increase rapidly, indicating a high sensitivity to NH₃ gas.