An apparatus is provided for focusing electrons being emitted from a
field emission device. The apparatus comprises a substrate (12,41,51) having first and second portions, and a
cathode metal layer (20,44,52) formed over the substrate (12,41,51) in the first portion to partially define a sidewall (23) for a trench (25) in the second portion. A
ballast layer (22,46,53) is formed over the substrate (12,41,51) in the second portion, the
cathode metal layer (20,44,52), and the sidewall (23). A first
dielectric layer (24,47,54) is formed over the
ballast layer (22,46,53) in the first portion. A gate extraction
metal layer (26,48,55) is formed over the first
dielectric layer. At least one emitter (30) comprising a high
aspect ratio conductive material is formed above the substrate and in the trench (25) having a sidewall (23) defined by the first
dielectric layer (24,47,54) and the
cathode metal layer (20,44,52). The
ballast layer (22,46,53) extends along the sidewall and conductively contacts the cathode metal layer and the at least one emitter. An
anode (32) is positioned to receive electrons from the at least one emitter (30). The ballast layer (22,46,53) provides a force that counteracts the sidewise pull of the gate extraction metal layer (26,48,55).