Characteristics of krypton ion emission from a gas field ionization source with a single atom tip

Abstract

A scanning ion beam instrument equipped with a gas field ionization source (GFIS) has been commercialized, but only helium and neon are currently available as GFISs. The characteristics of krypton ion emission from a single atom tip (SAT) have not been reported yet. In this study, the characteristics of krypton ion emission were investigated by field ion microscopy. At 65 K, the krypton ion emission current reached approximately 40 pA, which is 1 order of magnitude higher than that at 130 K. As the krypton gas pressure was increased, the krypton ion current increased. At a pressure of 0.3 Pa, the emission current was anticipated to reach 200 pA, which may be high enough for nanofabrication. The variation of the krypton ion current was as low as 5% in one hour. We concluded that a krypton ion beam instrument equipped with a GFIS will be a powerful tool for nanofabrication.

Characteristics Comparison of Neon, Argon, and Krypton Ion Emissions from Gas Field Ionization Sources with a Single-Atom Tip

“…The ion currents as a function of voltage (current-voltage characteristics) were also obtained at various temperatures. The krypton ion emissions were stable at the tip temperature of 65 K. Although neon and argon ion emissions have been reported (Kuo et al, 2006(Kuo et al, , 2008Livengood et al, 2011;Rahman et al, 2013;Shichi et al, 2017), it is difficult to compare our results with those reported for neon and argon ion emissions mainly because the atomic structures of the tips are different. The experimental conditions, such as emitter temperature and gas pressure, were not suitable to compare maximum possible currents.…”

“…Above the second-stage temperature of 40 K, there is a linear relationship between the tip-stem temperature and second cold-stage temperature. The tip-stem temperature is higher than the second cold-stage temperature by about 8 K (Shichi et al, 2017). The tip-stem temperature versus the second cold-stage temperature is shown in Figure 2b.…”

“…A schematic diagram of our FIM is shown in Figure 1. The details of this microscope were explained in our previous paper (Shichi et al, 2017). Our FIM has a double cold-stage Gifford-McMahon (GM) refrigerator, which has a cooling capacity of the second cold stage at 4.2 K of about 0.2 W. The second cold stage is connected to a tip holder ( Fig.…”

“…In our previous paper (Shichi et al, 2017), we reported on the characteristics of krypton ion emissions from an SAT prepared using the tungsten-fabrication method controlled by field-assisted reaction with nitrogen gas. The ion currents as a function of voltage (current–voltage characteristics) were also obtained at various temperatures.…”

Imaging and milling resolution of light ion beams from helium ion microscopy and FIBs driven by liquid metal alloy ion sources

“…Especially for very light ions, such as Li, LMAIS FIBs provide nearly the same milling resolution. Improvement is possible in both cases as GFIS technology can be extended to other gases [46][47][48]. Resolution improvements should be obtainable for both technologies using better optics and optimized platforms.…”