Field emission property of ZnO nanowires prepared by ultrasonic spray pyrolysis

• Field emission property of ZnO nanowires with various conditions was discussed.
• An optimum average length of nanowires is necessary for efficient field emission.
• The average diameter and sheet resistance of nanowires are important factors.
• A threshold voltage of 5.5 V/μm to obtain 1.0 μA/cm2 was achieved.

The field emission property of cold cathode emitters utilizing the ZnO nanowires with various conditions prepared by ultrasonic spray pyrolysis technique was discussed. It is found that the emission current was enhanced in the emitters having higher aspect ratio as well as smaller sheet resistance. Applying of post-annealing process, utilization of additional Mo back electrode in the cathode, and coating of Mo on the ZnO nanowires resulted in the improvement of the emission current and lowering the threshold voltage. A threshold voltage of about 5.5 V/μm to obtain 1.0 μA/cm2 was achieved in the sample prepared at the growth temperatures varying continuously from 250 °C to 300 °C.