This study reports on the secondary electron emission (SEE) performance of atomic layer deposited MgO films, with thicknesses in the range from 5 to 25 nm, for the application in the Timed Photon Counter. In this novel, photodetector MgO is utilized as a material for the fabrication of ultrathin transmission dynodes (tynodes). Two different types of PECVD silicon oxide films are applied on top of MgO, in order to protect it against etching steps in the fabrication of tynodes and also as a prevention against aging. Applicability of these two materials as capping films is evaluated in terms of achieved secondary electron yield (SEY) of MgO after their removal. Emission of secondary electrons is known to depend on numerous physical and chemical properties of the material, such as surface roughness and chemical composition. On that account, morphological and structural properties of modified MgO are determined by atomic force microscope and x-ray photoelectron spectrometer and linked to the changes in SEE behavior. The authors demonstrate that the application of a suitable capping layer followed by its removal provides an SEY of 6.6, as opposed to the value of 4.8 recorded from the as-deposited MgO film. Furthermore, in a following experiment, they showed that annealing of MgO films at high temperatures (up to 1100 °C) significantly improved the secondary electron emission, elevating the SEY to 7.2.

In this work we demonstrate how a novel single free electron detector 'Timed Photon Counter' (TiPC) may benefit from ultra-thin MgO transmission dynodes (tynodes). These membranes are fabricated through MEMS process technologies, with atomic layer deposition (ALD) as the most apt technique for growing films of good quality, with excellent control over thicknesses and extremely low surface roughness. Large area arrays of ultra-thin (5-25 nm) free-standing MgO membranes are fabricated and characterized to determine the optimal thickness for application of ALD MgO in TiPC. Supremacy of MgO over other materials previously considered, such as SiN, Al₂O₃, SiC, Si is verified. The exceptional mechanical (low stress in particular, -200 MPa), chemical and electrical properties of MgO make this material a very attractive candidate for numerous MEMS applications, as the MEMS transmission dynodes in the timed photon counter.