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.

Modeling electron emission and surface effects from diamond cathodes

“…Here, we explain first the simulation set up to model the dependence of the electron emission probability on applied field measured in the experiments done by Wang et al 10 . Then, we describe results from the simulations and compare them to the experimental data.…”

“…The 3D ES particle-in-cell computational capabilities together with the ability to efficiently model domains with multiple dielectrics in parallel have been of particular importance to enable the diamond-amplifier simulations reported here. These algorithms are needed to move particles between scattering events, to specify and maintain fields as in the two types of experiments 10 we simulated.…”

“…Erdong Wang et al 10 reported an approach to obtain probability of emission vs applied field from experimental data. In the simulations, we varied the external field from 2.1 MV/m to 17.1 MV/m to approximately cover the same range as in the experiments.…”

“…High-average current and high-brightness electron beams are needed in advance applications such as ultrahigh power Free-Electron Lasers 1 (FELs), electron cooling of hadron accelerators 2 , Energy-Recovery Linac (ERL) light sources 3 , and lasertron high-efficiency radiofrequency (RF) sources 4 . To address the high brightness requirements for these applications, a new design for a photoinjector with a diamond amplifier was proposed 5 and is currently being investigated [6][7][8][9][10][11] .…”

Theory of electron transport and emission from a semiconductor nanotip

“…24 In light of developing high-brightness, low emittance, fast response time, and long-lifetime electron sources, experimental study of secondary electron emission from hydrogen terminated diamond amplified photocathodes have been recently reported. [25][26][27] To interpret the experiment, secondary electron generation and transport in diamond has been modeled in 3D. 28 Subsequently, modeling of electron emission from a planar hydrogenated diamond surface accounting for associated band banding effect, effective mass anisotropy, and the inhomogeneity of electron affinity has been reported.…”