A high-brightness large-diameter graphene coated point cathode field emission electron source.

ABSTRACT: There have been several long-standing problems of cold field emission sources for electron microscopy and lithography that have prevented their widespread use, such as their inherent ultrahigh vacuum condition requirement (<10-9?torr), relatively poor current stability and rapid emission decay. This paper presents a cold field emission electron source which overcomes these problems based upon using a graphene-coated nickel point cathode. Preliminary experiments demonstrate that it provides stable emission for relatively large tip diameters (micron sizes), can operate in high vacuum conditions (>10-8?torr) and has an ultralow work function value of 1.10?±?0.07?eV. It has an estimated reduced brightness value of 1.46?×?109?A?m-2?sr-1?V-1 for cathode tip-radius of 170?nm and the measured energy spread ranges from 0.246?eV to 0.420?eV for a tip radii range of 260?nm to 500?nm, which is comparable to state-of-the-art conventional cold field emission sources.

SUBMITTER: Shao X 

PROVIDER: S-EPMC5876327 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature