Semiconductor hot-electron alternating current cold cathode

A ZnS semiconductor thin film grown on a dielectric layer is demonstrated as a cold cathode. Hot electrons are generated in ZnS and are emitted through a thin gold layer. Electron current density is controlled by means of alternating current (ac) coupling between the rear electrode and the ZnS layer. This yields a pulsating sheet source of electrons with controlled and spatially uniform current density. A current density of ∼1 μA/cm2 with efficiency of ∼10−3 is obtained. The ability to modulate and address this device makes it attractive for flat panel displays and other applications.