Xenon gas field ion source from a single-atom tip

Area of Science:

• Nanoscience and Nanotechnology
• Materials Science
• Physics

Background:

• Focused Ion Beam (FIB) systems are crucial for nanoscale research.
• Gas Field Ion Sources (GFISs) with atomic-size emitters provide high brightness for improved spatial resolution in FIB.

Purpose of the Study:

• To demonstrate a high-brightness Xenon (Xe+) ion beam using an Iridium/Tungsten (Ir/W) single-atom tip (SAT).
• To evaluate the performance and stability of the Xe+ ion beam across a range of temperatures for FIB applications.

Main Methods:

• Investigated ion emission current and extraction voltage for an Ir/W(111) SAT from 150 K to 309 K.
• Analyzed reduced brightness at a Xe gas pressure of 1 × 10⁻⁴ torr.
• Assessed emitter stability at elevated temperatures, including room temperature (RT).

Main Results:

• Achieved high-brightness Xe+ ion beams with excellent current stability.
• Demonstrated reduced brightness 2-3 orders of magnitude higher than Ga liquid metal ion sources and 4-5 orders higher than Xe inductively coupled plasma ion sources.
• The SAT emitter remained stable up to 309 K, with RT currents exceeding 1 pA at higher pressures, indicating feasibility for RT-Xe-GFIS.

Conclusions:

• The Xe-SAT-GFIS offers significant advantages over existing technologies due to its high brightness and stability at higher operating temperatures.
• Its operational temperature is higher than the cryogenic requirements for Helium Ion Microscopes (HIM), simplifying implementation.
• Xe-GFIS-FIB systems are poised to become powerful tools for nanoscale milling and secondary ion mass spectroscopy.