Fig. 4
ZnO NWs network electrical properties after heat treatment. a Typical current-voltage characteristics before and after annealing of pulling speed 2 mm min−1. The network channels showed Schottky contact behavior. (inset) I–V characteristics before annealing, magnified. b Resistance frequency distribution of ZnO NWs network pulled at speed of 2 mm min−1. Average resistance decreased for about three orders. (c) I–V characteristics at different back-gate voltages. Vg ranged from − 60 V to 60 V in 20 V steps. d Electrical properties of Ids vs Vg after heat treatment. e Comparison of I/Ioff ratio at different Vg values, before and after heat treatment (Vg step = 5 V). f Improved transconductance by heat treatment