Secondary electron emission characteristics of the Al2O3/MgO double-layer structure prepared by atomic layer deposition

Abstract

Abstract As a secondary electron emission layer, an Al2O3/MgO double-layer structure is fabricated by atomic layer deposition (ALD) technology. The thickness range from 1\xa0nm to 4\xa0nm of the top Al2O3 layer deposited on 20\xa0nm MgO creates a double-layer. The morphology of the cross section, element distribution, surface roughness, X-ray diffraction, and secondary electron yield (SEY) values were measured by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and secondary electron emission (SEE) measurement systems. The SEE characteristics of the MgO single layer, Al2O3 single layer and MgO/Al2O3 double-layer were measured. The maximum SEY of a single MgO layer reached 6.2@600\xa0eV, and the maximum SEY of a single Al2O3 layer reached 3.92@400\xa0eV. The SEY of the Al2O3/MgO double-layer decreased when the Al2O3 thickness ranged from 1\xa0nm to 4\xa0nm, and the SEY reduction value of the double-layer decreased as the Al2O3 thickness increased. Finally, Dionne s semiempirical SEE model was employed to explain the SEE yield of the prepared composite film structures. These results are useful for depositing a secondary electron emission layer in the channel of microchannel plates.