An apparatus for focusing electrons being emitted from a field emission
device comprises a cathode metal layer (20,44,52) formed over a first
portion of a substrate (12,41,51) to partially define a sidewall (23) for
a trench (25) in a second portion of the substrate. A ballast layer
(22,46,53) is formed over 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 and a gate
extraction metal layer (26,48,55) is formed thereover. At least one
emitter (30) is formed above the substrate and in the trench (25) having
the 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 and provides a force that counteracts the
sidewise pull of the gate extraction metal layer (26,48,55).