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.