Gate-controlled ZnO nanowires for field-emission device application

Gate-controlled field-emission devices have great promise for a number of applications such as bright electron source or flat display array. The gate-controlled ZnO nanowire (NW) field-emission device was fabricated using lift-off fabrication process to synthesize side-gate control in the present investigation. This device effectively controls the turn-on electron beams and switches the drain current ( I d ) under a threshold gate voltage ( V T ) of ∼ 35 V . In the meantime, the current density of the device is ∼ 1 mA ∕ cm 2 that is similar to carbon nanotube (CNT) field-emission level with a potential for the design of field-emission display (FED) devices. Furthermore, when the gate voltage ( V g ) is equal to 0 V , the turn-on electric field ( E to ) for ZnO NWs is ∼ 0.8 V ∕ μ m and the effective-field-enhancement factor β is ∼ 7000 . As V g is increased to 10, 20, 30, and 40 V , the E to lowers to the range of ∼ 0.8 – 0.6 V ∕ μ m and the β value increases to ∼ 7600 – 17 800 . The continuous increases in V g lowers the turn-on electric field because the local electric field ( E local ) generated induces an extra force that enhances electron emission from the ZnO NWs. Besides, the transconductance ( g m ) value can approach 0.388 mS while the V g is increased to 44.5 V . The devices have well-controlled behavior and exhibit better Fowler-Nordheim characteristic in comparison with classic CNT field-emission devices. The gated ZnO NW array has a good opportunity to be applied to FED devices and be integrated to the semiconductor industry in the future.