Particulate Generation on Surface of Iron Selenide Films by Air Exposure

TL;DR

This study investigates the formation of nanometer-sized particulates on iron selenide (FeSe) films upon air exposure, which hinders their use in superconducting transistors, and analyzes their chemical composition.

Contribution

The paper reveals that particulate formation on FeSe films occurs without chemical composition change, suggesting physical or light-element interactions as the cause.

Findings

Particulates form immediately after air exposure.

Chemical analysis shows no significant compositional difference.

Particulates are likely due to light elements in air.

Abstract

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.