Transparency of graphene for low-energy electrons measured in a vacuum-triode setup

Abstract

Graphene, being an atomically thin conducting sheet, is a candidate material for gate electrodes in vacuum electronic devices, as it may be traversed by low-energy electrons. The transparency of graphene to electrons with energies between 2 and 40 eV has been measured by using an optimized vacuum-triode setup. The measured graphene transparency equals ∼60% in most of this energy range. Based on these results, nano-patterned sheets of graphene or of related two-dimensional materials are proposed as gate electrodes for ambipolar vacuum devices.

Magnetic-field-free thermoelectronic power conversion based on graphene and related two-dimensional materials

“…The thermal robustness of graphene has been demonstrated in Ref. 15 where the transparency of low energy electrons was measured in a triode setup similar to the one discussed here.…”

“…The measured data of the graphene transparency in a triode setup given in Ref. 15 include these losses and they are therefore taken into account in our efficiency considerations below.…”

“…As was recently found, however, under operation conditions viable for thermoelectronic generators, graphene has an electron absorption of only $40% for electrons with energies in the relevant energy range of 2-40 eV crossing the graphene perpendicular to the plane. 15 Graphene or related twodimensional materials therefore offer the possibility to realize electron-transparent gates for thermoelectronic energy conversion. Without magnets, such generators have very little mass, even more if operated in the vacuum of outer space.…”

Sub-GeV dark matter detection with electron recoils in carbon nanotubes

“…On the contrary, electrons injected in the body of nanotubes (or in the interstices) by DM-electron scatterings, might go through the walls, with definite transmission coefficients, and undergo multi-scattering events, crossing several nanotubes, before exiting from the array. As a benchmark for our analysis, we have used the results of some experimental studies on the determination of transmission coefficients of electrons through graphene planes [12][13][14][15][16]. More information from experiments of this kind would be extremely useful for determining directly also reflection and absorption coefficients.…”

“…Indeed in the experiments reported in [12][13][14][15][16] it is found that the largest part of the electron beam impinging orthogonally to the graphene monolayer (deposited on a surface with holes) is transmitted or reflected.…”