An active matrix display comprising an array of gate-controlled surface-conduction electron-emitter devices (GC_SEDs). Each gate-controlled_surface-conduction electron-emitter device (GC_SED) comprises a first electrode, and a pair of (second and third) electrodes that are insulated from the first electrode and that are spaced apart from each other to bound an electron-emitting area overlapping the first electrode. The potential barrier in the electron-emitting area (slit) between the second and third electrodes is modulated (controlled, switched) by applying a voltage to the first electrode that serves as a gate that effectively controls the tunneling of the electrons, between the second and third electrodes. Efficient electron tunneling is allowed through modulation of potential barrierby the first electrode functioning as a gate even though the distance (width of the electron-emitting area, slit) between the second and third electrodes may be significantly more than 10 nanometers.