Secondary-electron emission from hydrogen-terminated diamond: Experiments and model

Abstract

A hydrogen-terminated diamond is a proven efficient electron emitter that can support emission of high average current. Several factors dictate the amplifier’s gain: the number of secondary electrons created at their point of entry into the diamond, the fraction of created electrons transmitted to the emitting face, and the fraction of transmitted electrons emitted. In this paper, we present a model detailing the impact of charge trapping at the surface on the instantaneous electric field inside the diamond, and its effect on the transmission gain. The ratio of instantaneous emitted electrons to the transmitted electrons depends on the electron’s energy distribution and the surface barrier. We calculated the latter by evaluating the magnitude of the negative-electron affinity that is modified by the Schottky effect due to the presence of the external applied field. The instantaneous values then were time integrated to yield the time-averaged ratio of the number of emitted electrons to the transmitted ones. The findings from the model agree very well with our experimental measurements. As an application of the model, we estimate the energy spread of the electrons inside the diamond from the measured secondary-electron emission.