  Field electron emission from an ultrathin multilayer planar cold cathode
(UMPC) including quantum well structure has been both experimentally and
theoretically investigated. We found that only tuning the energy levels of UMPC
the field electron emission (FE) characteristic can be evidently improved,
which is unexplained by the conventional FE mechanism. Field electron emission
mechanism dependent on the quantum structure effect, which supplies a favorable
location of electron emission and enhances tunneling ability, has been
presented to expound the notable amelioration. An approximate formula brought
forward can predict the quantum FE enhancement, which the theoretical
prediction is close to the experimental result.
