Field-Assisted Oxygen Etching for Niobium Nanotip
Yi-Fang Chen1*, Quan-You Huang1, Ing-Shouh Hwang2, Tsu-Yi Fu1
1Department of Physics, National Taiwan Normal University, Taipei, Taiwan
2Institute of Physics, Academia Sinica, Taipei, Taiwan
* presenting author:Yi-Fang Chen,
A straightforward modification technique for poly-crystal niobium tips in UHV was studied. The modification technique is based on espeacilly controlling the reaction of oxygen gas with the surface atoms of a niobium tip in a field ion microscope (FIM). Confining this field-assisted etching reaction to the shank has enabled us to produce niobium nano- tips. Nano-tip formation is evident from the decrease in the FIM imaging voltage and the decrease in the apex area. Field-assisted etch niobium tip was carried out at three different temperature (25 K,50 K,80 K). Then we compare the etching efficiency and FIM image quality were compared.

We measure the field emission electron current form the etched nano-tip and illustrate the F-N plot. The F-N plot shows that the shape of the etched tip will change after thermal treatment. We also measure the stability of the field emission current from the etched niobium nano-tip in 30 minute. When the emission electron current is 434 pA, the instability is less than 10%.

Keywords: field emission, niobium, field-assisted etching, FIM