The construction and characterization of MgO transmission dynodes
HW Chan (Nikhef, TU Delft - Electronic Components, Technology and Materials)
Violeta Prodanovic (Nikhef, TU Delft - EKL-Users)
A. M.M.G. Theulings (TU Delft - RST/Neutron and Positron Methods in Materials)
S. Tao (Eindhoven University of Technology)
J. Smedley (Stanford University)
Kees Hagen (TU Delft - ImPhys/Hagen group)
Pasqualina M Sarro (TU Delft - Electronic Components, Technology and Materials)
H. v.d. Graaf (Nikhef)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
In this work we demonstrate that ultra-thin (5 and 15 nm) MgO transmission dynodes with sufficient high transmission electron yield (TEY) can be constructed. These transmission dynodes act as electron amplification stages in a novel vacuum electron multiplier: the Timed Photon Counter. The ultra-thin membranes with a diameter of 30 μm are arranged in a square 64-by-64-array. The TEY was determined with a scanning electron microscope using primary electrons with primary energies of 0.75-5 keV. The method allows a TEY map of the surface to be made while simultaneously imaging the surface. The TEY of individual membranes can be extracted from the TEY map. An averaged maximum TEY of 4.6±0.2 was achieved by using 1.35 keV primary electrons on a TiN/MgO bi-layer membrane with a layer thickness of 2 and 5 nm, respectively. The TiN/MgO membrane with a layer thickness of 2 and 15 nm, respectively, has a maximum TEY of 3.3±0.1 (2.35 keV). Furthermore, the effect of the electric field strength on transmission (secondary) electron emission was investigated by placing the emission surface of a transmission dynode in close proximity to a planar collector. By increasing the electric potential between the transmission dynode and the collector, from -50 V to -100 V, the averaged maximum TEY improved from 4.6±0.2 to 5.0±0.3 at a primary energy of 1.35 keV with an upper limit of 5.5 on one of the membranes.
help_outline