Enhancing field emission in ultrascaled
electronics improves the
device performance and energy efficiency. Conventional lithography
defines electrodes with a few-nanometer spacing on the cost of strengthened
electron scattering and the reduced field enhancement factor, thus
presenting challenges to enhance field emission at a small bias. Here,
we used self-assembled nanorods with sub-5 nm spacing as electrodes
to overcome these challenges. Intrinsic ballistic transport through
high-crystallinity solution-synthesized nanorods minimized charge
scattering; meanwhile ultrascaled anisotropic morphologies concentrated
local electric fields and thereby lowered the barrier height. Enabled
by these structural features, we demonstrated field emission density
up to 4.1 × 104 A cm–2 at 1 V in
air, more than 10-fold higher than typical molecular and vacuum electronics
at similar conditions, and constructed an air-operating electron source
with an on/off ratio of 105 at the collector electrode.
Energy-efficient high-conductance electron emission suggested the
potential of using solution-synthesized nanomaterials in ultrascaled
electronics.