The authors investigated the performance of ZnO nanowire-based metal–semiconductor field effect transistors (MESFETs) by focusing electron beam on the Schottky gate. The MESFET was fabricated by employing Tantalum as drain and source and by using Schottky barrier at tungsten–ZnO interface as the gate. As to I_DS against V_GS curves, once the gate was illuminated with electron beam radiation, crests with a redshift as V_DS increased and a p-type semiconductor transistor behaviour were observed. At the critical points, the value of V_DS−V_GS revealed a linear behaviour with the increasing V_DS. The authors attributed these results to the gain enhanced by electron beam radiation and carrier-trapping process, while the shift may be associated with the image-force lowing effect.