Modification of the emission surface of a carbonized iridium field emitter during the adsorption of barium atoms

Field electron microscopy was used to study the modification of the emission surface of a carbonized iridium field emitter when the concentration of barium atoms on the surface changes within the monolayer coating. When barium atoms are adsorbed at a temperature of $T$ = 300 K, no significant changes in the field electronic images of the emission surface are observed. The formation of barium islands on graphene in the region of the (100) iridium face at the annealing temperature $T$ = 1200 K was detected. At the annealing temperature $T$ = 1500 K, the barium island is dissolved and graphene is intercalated by barium atoms. The emission surface increases and becomes uniform in emission.