  Nanometer-sized particular structures are generated on the surfaces of FeSe
epitaxial films directly after exposure to air; this phenomenon was studied in
the current work because these structures are an obstacle to field-induced
superconductivity in electric double-layer transistors using FeSe channel
layers. Chemical analyses using field-effect scanning Auger electron
spectroscopy revealed no clear difference in the chemical composition between
the particular structures and the other flat surface region. This observation
limits the possible origins of the particulate formation to light elements in
air such as O, C, H, and N.
