Abstract: An electron source is disclosed in which control signals having transition times less than about 10 nanoseconds and electrically isolated from a gated photocathode control an electron beam supplied by the gated photocathode. In one embodiment, the electron source includes a transmissive substrate, a photoemitter on the substrate, a gate insulator on the photoemitter, a gate electrode on the gate insulator, a housing enclosing the photoemitter and the gate electrode, a light source located outside the housing, and a detector located in the housing to receive light from the light source. The detector is electrically coupled to control a voltage applied to one of the gate electrode or the photoemitter.

Abstract: A photocathode emitter as a source of electron beams, having an optically transmissive substrate patterned to define a protrusion, heat conducting material occupying the space surrounding the protrusion, and a photoemitter layer over the protrusion. The photoemitter is positioned on the side of the substrate opposite the surface on which the illumination is incident, and has an irradiation region at the contact with the top of the protrusion patterned on the substrate, and an emission region opposite the irradiation region, these regions being defined by the path of the illumination. The heat conducting material around the protrusion conducts heat away from this focused region of illumination on the photocathode to allow higher currents to be achieved from the photocathode and thus permits higher throughput rates in applications including electron beam lithography. In one version, the photocathode is fabricated using microfabrication techniques, to achieve a small emission spot size.