Intense microsecond electron pulses from a Schottky emitter

Thanks to their high brightness, field emitters are the electron sources of choice in most high-end electron microscopes. Under typical operating conditions, the available emission current from these emitters is largely limited by practical considerations, and extracting significantly larger currents is usually not possible without reducing the lifetime of the emitter or even damaging it. Such limitations may however not apply if the emitter is only briefly subjected to extreme operating conditions, so that damage can be outrun. Here, we demonstrate that it is possible to temporarily operate a Schottky emitter far outside its stable operating regime and significantly increase its emission current. We do so by locally heating the tip of the emitter with a microsecond laser pulse, which boosts the emission current by a factor of 3.7, to nearly 450 μA. We believe that the generation of intense, microsecond electron pulses from a field emitter will particularly benefit atomic-resolution imaging of fast processes that occur on the microsecond timescale.