Low fluctuation and drift of field emission currents emitted from Pd/W nanotips

The authors have observed the fluctuation and drift of field emission (FE) current from nanotips fabricated by the deposition of Pd under extreme high vacuum and subsequent annealing at ∼ 1000 K . Observed fluctuations of 0.02%–1% for 100 h at ∼ 10 nA were extremely low when compared with those of conventional FE guns (a few percent). From a practical point of view, drifts in FE current were negligible over several hours. When the Pd layer had been removed by repeated heating and FE operation, Pd redeposition on the tip apex was necessary for their restoration.