Surface conduction emitters for use in field emission display devices

Abstract

For use in cathodoluminescent field emission display devices, a gated channel layer of an inverted field effect transistor functions as the electron emissive layer for a flat film surface conduction cathode emitter. In such emitters, electrons are emitted from the surface of a flat thin emissive film when an electric current is caused to flow through the film in parallel with the surface of the film. An electric field caused by a variable voltage source being applied to the gate of the transistor can control the conductivity of the channel layer, thereby controlling the level of electron emissions from the cathode emitter structure. In a variation, the field effect transistor is constructed with a two-tier structure that during operation is designed to keep conduction near the surface of the transistor. As a result, this device pushes electrons towards the exposed surface where they can then escape from the channel layer to bombard the cathodoluminescent phosphor anode. To ensure against unwanted anode currents, electron blocking junction elements can be incorporated on either side or both sides of the channel and positioned over a widened gate electrode, such that they are commonly gated along with the channel to respond to a single control voltage input to the gate electrode. Further, such emitter structures can incorporate a thin near mono-molecular film of a high secondary electron emission material on the surface of the electron emissive layer, to generally enhance the level of electron emissions from the emitter.